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SJC-11967

                COMMONWEALTH   vs.   THOMAS J. GERHARDT.

         Worcester.    January 6, 2017. - September 19, 2017.

 Present:     Gants, C.J., Lenk, Hines, Gaziano, Lowy, & Budd, JJ.1


Marijuana. Motor Vehicle, Operating under the influence.
     Evidence, Field sobriety test.



     Complaint received and sworn to in the Worcester Division
of the District Court Department on April 24, 2013.

     A motion for a hearing to challenge the admissibility of
certain evidence was heard by Andrew M. D'Angelo, J., and
questions of law were reported by him to the Appeals Court.

     The Supreme Judicial Court granted an application for
direct appellate review.


     Rebecca A. Jacobstein, Committee for Public Counsel
Services, for the defendant.
     Michelle R. King, Assistant District Attorney, for the
Commonwealth.
     Steven S. Epstein & Marvin Cable, for National Organization
for the Reform of Marijuana Laws, amicus curiae, submitted a
brief.
     Michael A. Delsignore & Julie Gaudreau, for National
College for DUI Defense, amicus curiae, submitted a brief.



     1
       Justice Hines participated in the deliberation on this
case prior to her retirement.
                                                                      2


    GAZIANO, J.   In this case we are asked to consider the

admissibility of field sobriety tests (FSTs) where a police

officer suspects that a driver has been operating under the

influence of marijuana.     Police typically administer three

FSTs -- the "horizontal gaze nystagmus test," the "walk and turn

test" and the "one leg stand test" -- during a motor vehicle

stop in order to assess motorists suspected of operating under

the influence of alcohol or other drugs.     These tests were

developed specifically to measure alcohol consumption, and there

is wide-spread scientific agreement on the existence of a strong

correlation between unsatisfactory performance and a blood

alcohol level of at least .08%.

    By contrast, in considering whether a driver is operating

under the influence of marijuana, there is as yet no scientific

agreement on whether, and, if so, to what extent, these types of

tests are indicative of marijuana intoxication.     The research on

the efficacy of FSTs to measure marijuana impairment has

produced highly disparate results.     Some studies have shown no

correlation between inadequate performance on FSTs and the

consumption of marijuana; other studies have shown some

correlation with certain FSTs, but not with others; and yet

other studies have shown a correlation with all of the most

frequently used FSTs.     In addition, other research indicates
                                                                      3


that less frequently used FSTs in the context of alcohol

consumption may be better measures of marijuana intoxication.

     The lack of scientific consensus regarding the use of

standard FSTs in attempting to evaluate marijuana intoxication

does not mean, however, that FSTs have no probative value beyond

alcohol intoxication.    We conclude that, to the extent that they

are relevant to establish a driver's balance, coordination,

mental acuity, and other skills required to safely operate a

motor vehicle, FSTs are admissible at trial as observations of

the police officer conducting the assessment.     The introduction

in evidence of the officer's observations of what will be

described as "roadside assessments" shall be without any

statement as to whether the driver's performance would have been

deemed a "pass" or a "fail," or whether the performance

indicated impairment.    Because the effects of marijuana may vary

greatly from one individual to another, and those effects are as

yet not commonly known, neither a police officer nor a lay

witness who has not been qualified as an expert may offer an

opinion as to whether a driver was under the influence of

marijuana.2

     1.   Background.   a.   Prior proceedings.   Following a motor

vehicle stop, Thomas Gerhardt was charged in the District Court

     2
       We acknowledge the amicus briefs in support of the
defendant submitted by the National College for DUI Defense and
the National Organization for the Reform of Marijuana Laws.
                                                                     4


with operating a motor vehicle under the influence of marijuana,

in violation of G. L. c. 90, § 24.     Gerhardt filed a motion for

a Daubert-Lanigan hearing, seeking to challenge the

admissibility of evidence concerning his performance on FSTs

conducted after the stop.     See Daubert v. Merrell Dow Pharms.,

Inc., 509 U.S. 579, 592-595 (1993); Commonwealth v. Lanigan, 419

Mass. 15, 24-27 (1994).     After an evidentiary hearing, a

District Court judge reported four questions to the Appeals

Court, pursuant to Mass. R. Crim. P. 34, as amended, 442 Mass.

1501 (2004).

         "1. Whether police officers may testify to the
    administration and results of standard [FSTs] in
    prosecutions for [o]perating [u]nder the [i]nfluence of
    [m]arijuana as they do in [o]perating [u]nder the
    [i]nfluence of [a]lcohol prosecutions?

         "2. Are the effects of marijuana consumption
    sufficiently within the common knowledge and experience of
    a lay person, such that a non-expert witness may offer
    opinion evidence whether a person is 'high' on marijuana?

         "3. May a police officer, who has not been qualified
    as an expert witness, testify to the effects of marijuana
    on a person such as bloodshot eyes, lack of coordination
    and/or balance, reaction times, slow speech, paranoia, or
    relaxed responses[?]

         "4. May a juror rely on their own experience and
    common sense about the effects of marijuana as they may do
    in an [o]perating [u]nder the [i]nfluence of [a]lcohol
    prosecution?" [footnote omitted].

    We granted Gerhardt's application for direct appellate

review.   After oral argument, we remanded the matter to the

District Court judge who had reported the questions for further
                                                                        5


findings on eleven specific issues.       Following the return of the

judge's findings, we again heard oral argument in the matter.

     b.    Facts.    The parties submitted a statement of agreed

facts as to the evidence that the Commonwealth would seek to

present at trial.       On February 13, 2013, at approximately

12:20 A.M., Trooper French of the State police3 observed a blue

Suzuki Grand Vitara motor vehicle traveling south on Route 146,

without the rear lights on.       French followed the vehicle as it

left Route 146 at exit 8.       He activated his emergency lights and

stopped the vehicle on Elmwood Street in Millbury.

     French approached the vehicle on the passenger side.        There

were three occupants in the vehicle:       the driver, later learned

to be Gerhardt, and two passengers.       French saw smoke inside the

vehicle, and, as soon as the front passenger window was lowered,

he detected "the distinct odor of burnt marijuana."       He also saw

a large amount of what he identified as cigar tobacco on the

floor, and a cigar slicer on the key ring in the ignition.       The

trooper asked the driver for his driver's license and

registration.       Gerhardt handed him the license and said that he

did not have his registration.

     French asked Gerhardt how much marijuana was in the

vehicle.    Gerhardt responded that there were "a couple of

roaches" in the ashtray; he pulled two largely-consumed rolled

     3
         Trooper French's first name is not apparent in the record.
                                                                     6


cigarettes from the ashtray and handed them to French.     French

then asked when the occupants had smoked marijuana.    One of the

passengers responded that they had smoked about twenty minutes

previously.    Gerhardt said that it had been about three hours

earlier.   French walked to the driver's side of the vehicle and

noticed that the light switch was in the "off" position.     He

asked Gerhardt how much he had smoked.    Gerhardt responded that

he had smoked approximately one gram of marijuana.

     French then asked Gerhardt to step out of the vehicle to

perform FSTs.    French administered a number of FSTs, including

the horizontal gaze nystagmus test (HGN);4 the nine-step walk-

and-turn test (WAT); and the one-leg-stand test (OLS).     French

also asked Gerhardt to recite the alphabet from D to Q and to

count backward from seventy-five to sixty-two.

     Gerhardt had no nystagmus indicators, and was able to

recite the requested portion of the alphabet and to count

backwards.    He did not perform the WAT as instructed, even after


     4
       "Nystagmus is '[a]n abnormal and involuntary movement of
the eyeballs from side to side or up and down, but usually from
side to side.'" Commonwealth v. Sands, 424 Mass. 184, 186
(1997), quoting State v. Merritt, 36 Conn. App. 76, 84 (1994).
An officer administers the HGN test by having the subject focus
on a moving object and observing whether the subject is able to
follow the object smoothly with his or her eyes, whether the
subject's eyes bounce at the extremes of the field of vision,
and whether they exhibit nystagmus, where there is an angle of
less than forty-five degrees between the eyes and the object.
Sands, supra at 186-187. Introduction of the results of this
test at trial requires expert testimony. See id. at 188.
                                                                     7


several explanations and a demonstration by the trooper in

response to Gerhardt's first answer in the negative when asked

whether he understood the instructions.     Rather than standing

heel to toe, with his right foot in front and his left toes

touching his heel, as he had been shown, Gerhardt moved his feet

so that they were side by side; he also did not turn around as

instructed.   French determined that "the results of this test

indicated that Gerhardt was impaired."    The trooper then

provided instructions and gave a demonstration of the OLS test,

and Gerhard indicated that he understood.     In performing the

test, however, Gerhard did not remain upright on one foot,

instead putting his foot down multiple times, and swayed.

French determined that "the results of this test indicated that

Gerhardt was impaired."

    After administering these tests, French concluded that

Gerhardt was under the influence of marijuana.     French informed

Gerhardt that he was not under arrest, but had him sit in the

back of French's cruiser.   Both passengers were asked to step

out of the vehicle and were pat frisked.     They, too, were told

that they were not under arrest, and were placed in the back

seat of the cruiser.   A second trooper arrived at the scene.

During a search of the vehicle, the troopers recovered two more

marijuana "roaches" and a marijuana stem.
                                                                        8


     On April 24, 2013, a criminal complaint issued against

Gerhardt charging him with operating a motor vehicle while under

the influence of drugs, pursuant to G. L. c. 90,

§ 24 (1) (a) (1), and traffic violations.

     2.    Discussion.   a.   Field sobriety tests.   The FSTs, which

were designed to detect alcohol impairment, are administered and

evaluated in a standardized manner.      The two tests primarily

administered in the context of alcohol impairment are the WAT

and the OLS, which are designed to assess an individual's

balance, coordination, dexterity, ability to follow directions,

and ability to focus attention on multiple subjects at the same

time.5

     In performing the WAT, the subject is directed to take nine

steps, walking heel-to-toe, along a real or imaginary straight

line.     The subject then turns on one foot and returns in the

same manner.    An officer administering the WAT looks for eight

specific indicators of impairment:     losing balance while

listening to the instructions, beginning before the instructions

are finished, stopping to regain balance while walking, failing

to walk heel-to-toe, stepping off the line, using arms to


     5
       There are a number of other FSTs, such as the "Romberg
balance test," in which the subject stands with heels and toes
together and arms at the side of the body and tips his or her
head back slightly and estimates the passage of thirty seconds,
and the "finger to nose test," which are less frequently used in
the context of alcohol impairment.
                                                                    9


balance, making an improper turn, or taking an incorrect number

of steps.   Where the consumption of alcohol is at issue, there

is an established correlation between performance on the test

and blood alcohol content (BAC), with some research indicating

that as many as seventy-nine per cent of individuals who exhibit

two or more of these indicators have a BAC of 0.08 per cent or

higher.

     In performing the OLS, the subject stands with one foot

raised approximately six inches off the ground while counting

aloud for thirty seconds.   An officer conducting the test looks

for four indicators of impairment:   swaying while balancing,

using arms to balance, hopping to maintain balance, and putting

the foot down.   Research has indicated that as many as eighty-

three per cent of individuals who exhibit two or more of these

indicators have a BAC of 0.08 per cent or higher.

     b.   Admissibility of the FSTs in the context of marijuana.

While using marijuana is no longer a crime in Massachusetts for

adults who are at least twenty-one years old,6 operating a motor

vehicle while under the influence of marijuana remains a

criminal offense.   See G. L. c. 90, § 24.   In a prosecution for

operating while under the influence of marijuana, it is the

Commonwealth's burden to prove beyond a reasonable doubt, in


     6
       See St 2016, c. 334, "The Regulation and Taxation of
Marijuana Act."
                                                                  10


addition to the other elements of the offense, that a

defendant's consumption of marijuana impaired his or her ability

to drive a motor vehicle safely.   See Commonwealth v. Daniel,

464 Mass. 746, 756 (2013), quoting Commonwealth v. Connolly, 394

Mass. 169, 173 (1985) (in prosecution for operating under

influence of alcohol or marijuana, the Commonwealth "need not

prove that the defendant actually drove in an unsafe or erratic

manner, . . . [but] it must prove a diminished capacity to

operate safely").

    Unlike alcohol, marijuana does not act as a general central

nervous system depressant, impairing functions throughout the

body.   Nonetheless, the primary psychoactive substance in

marijuana, tetrahydrocannibol (THC), is known to have an impact

on several functions of the brain that are relevant to driving

ability, including the capacity to divide one's attention and

focus on several things at the same time, balance, and the speed

of processing information.   While not all researchers agree, a

significant amount of research has shown that consumption of

marijuana can impair the ability to drive.    There is ongoing

disagreement among scientists, however, as to whether the FSTs

are indicative of marijuana impairment.   In recent years,

numerous studies have been conducted in an effort to determine

whether a person's performance on the FSTs is a reliable
                                                                    11


indicator of impairment by marijuana.7     These studies have

produced mixed results.8     For example, researchers found that the

FSTs were mildly sensitive to the effects of marijuana, with the

OLS being the most sensitive.     That study, however, also

indicated that the OLS produced numerous false positives.9       Other

researchers found that the OLS was a somewhat more reliable

indicator of marijuana impairment than the WAT.10    In a more

recent study, by contrast, a different group of researchers

found that the WAT was a better indicator of marijuana

impairment than the OLS.11    Researchers conducting another study

found that marijuana significantly impaired performance on the


     7
       The judge noted several of these studies in his findings
on remand from this court. In addition, both parties provided
numerous such studies in the record, and one of the amici did as
well.
     8
       The number of studies in this field is vast; we cite only
a few representative examples.
     9
       Bosker, Theunissen, Conen, Kuypers, Jeffery, Walls,
Kauert, Toennes, Moeller, & Ramaekers, A Placebo-Controlled
Study to Assess Standardized Field Sobriety Tests Performance
During Alcohol and Cannabis Intoxication in Heavy Cannabis Users
and Accuracy of Point of Collection Devices for Detecting THC in
Oral Fluid, 223 Psychopharmacology 439, 443-444 (2012) (Bosker).
     10
       Papafotiou, Carter, & Stough, An Evaluation of the
Sensitivity of the Standardized Field Sobriety Tests (SFSTs) to
Detect Impairment Due to Marijuana Intoxication, 180
Psychopharmacology 107, 113 (2005) (Papafotiou).
     11
       Declues, Perez, & Figueroa, A 2-Year Study of Delta-9-
tetrahydrocannabinol Concentrations in Drivers: Examining
Driving and Field Sobriety Test Performance, 61 J. Forensic
Sciences 1664, 1669 (2016).
                                                                  12


HGN, the WAT, and the OLS.12    Other studies have shown no

correlation between performance on the HGN and consumption of

marijuana, even where the OLS or WAT showed some sensitivity to

marijuana consumption,13 while others have found no correlation

between the consumption of marijuana and any of these FSTs.14

     As a result of these varied results, some researchers have

suggested development of another group of FSTs, combining the

currently less-frequently used Romberg stand test and the nose-

touch test, see note 5, supra, with a to-be-developed test on

pupil constriction,15 or adding a scoring factor of head

movements or jerks to the standard FSTs.16    Other researchers are

working on a tongue or cheek swab test that directly measures

levels of THC shortly after consumption.17    It is clear from the

above, as the judge stated in his findings on remand, that the

scientific community has yet to reach a consensus on the

     12
          Papafotiou, supra at 111-113.
     13
       Hartman, Richman, Hayes, & Heustis, Drug Recognition
Expert (DRE) Examination Characteristics of Cannabis Impairment,
92 Accident Analysis and Prevention 219, 226 (2016) (Hartman).
     14
       See generally Neavyn, Blohm, Babu, & Bird, Medical
Marijuana and Driving: a Review, 10 J. Med. Toxicol. 269
(2014); Jones, Donnelly, Swift, & Weatherburn, Driving Under the
Influence of Cannabis: The Problem and Potential
Countermeasures, 87 Crime & Justice Bulletin 1 (2005).
     15
          See Hartman, supra at 226.
     16
          See Papafotiou, supra at 108.
     17
          See Bosker, supra at 442, 445.
                                                                  13


reliability of FSTs to assess whether a driver is under the

influence of marijuana.

    The lack of scientific agreement, however, does not, by

itself, resolve the question whether a driver's performance on

an FST is relevant evidence in a trial on a charge of operating

under the influence of marijuana.   " The relevance threshold for

the admission of evidence is low.   'Evidence is relevant if it

has a "rational tendency to prove an issue in the case,"'"

Commonwealth v. Arroyo, 442 Mass. 135, 144 (2004), quoting

Commonwealth v. LaCorte, 373 Mass. 700, 702 (1977), or to

"render a 'desired inference more probable than it would be

[otherwise],'"   Arroyo, supra, quoting Commonwealth v.

Fayerweather, 406 Mass. 78, 83 (1989).   To be relevant, evidence

"need not establish directly the proposition sought; it must

only provide a link in the chain of proof."    Commonwealth v.

Sicari, 434 Mass. 732, 750 (2001), cert. denied, 534 U.S. 1142

(2002), quoting Commonwealth v. Yesilciman, 406 Mass. 736, 744

(1990).

    The absence of scientific consensus regarding the use of

standard FSTs in attempting to evaluate marijuana intoxication

does not mean that they have no probative value.    A police

officer makes numerous relevant observations in the course of an

encounter with a possibly impaired driver.    There is no doubt

that an officer may testify to his or her observations of, for
                                                                   14


example, any erratic driving or moving violations that led to

the initial stop; the driver's appearance and demeanor; the odor

of fresh or burnt marijuana; and the driver's behavior on

exiting the vehicle.

     In our view, certain of the FSTs also may provide

information that is relevant to the question of a defendant's

impairment, and a police officer may testify, as a lay witness,

to his or her observations of the defendant's performance.    In

particular, observations of the performance of the OLS and the

WAT may be admissible as evidence of a defendant's balance,

coordination, ability to retain and follow directions, and

ability to perform tasks requiring divided attention, and the

presence or absence of other skills necessary for the safe

operation of a motor vehicle.18   We see no reason why an

officer's observations of a defendant's behavior on being asked

to walk a straight line or to stand on one foot should be


     18
       The HGN stands on a different footing from the FSTs that
are directed to balance and coordination. We previously have
held that, in a prosecution for operating under the influence of
alcohol, "the HGN test relies on an underlying scientific
proposition and therefore expert testimony is required." See
Sands, 424 Mass. at 188. In addition, "there must be a
determination as to the qualification of the individual
administering the HGN test and the appropriate procedure to be
followed if the HGN test results are to be admitted at trial."
Id. We reached this result because the correlation between
alcohol intoxication and nystagmus is not within the common
experience of jurors. Id. In the context of marijuana, any
correlation between nystagmus and intoxication is even further
beyond jurors' common knowledge and experience.
                                                                     15


excluded because the scientific community's understanding of

precisely how this correlates with marijuana use is still

evolving.   We are not persuaded, however, that the FSTs can be

treated as scientific tests establishing impairment as a result

of marijuana consumption.     The scientific community has not

reached a consensus as to whether a defendant's performance on

any combination of FSTs, or on any individual FST, is correlated

with marijuana use or impairment.

    The unsettled state of the scientific research suggests

that FST evidence neither should be treated as a definitive test

of impairment nor excluded entirely from consideration by the

finder of fact.   Cf. Commonwealth v. Thomas, 476 Mass. 451, 464

(2017) (where there is no consensus that simultaneous display of

photographs is inferior to sequential display, "the

decision . . . is best left to law enforcement, and the choice

will continue to bear on the weight of the identification, but

not on its admissibility").     Moreover, that marijuana can cause

impairment of skills necessary to driving, such as coordination,

concentration, and the ability to divide one's attention among

multiple tasks is within the common experience and knowledge of

jurors.   A police officer testifying to a defendant's

performance on these FSTs therefore need not be qualified as an

expert, and such evidence may be admitted without satisfying the

Daubert-Lanigan requirements.     A police officer may not suggest,
                                                                   16


however, on direct examination that an individual's performance

on an FST established that the individual was under the

influence of marijuana.19   Likewise, an officer may not testify

that a defendant "passed" or "failed" any FST, as this language

improperly implies that the FST is a definitive test of

marijuana use or impairment.20

     Indeed, the word "test" itself inadvertently may lend "an

aura of scientific validity."    See United States v. Horn, 185 F.

Supp. 2d 530, 559 (D. Md. 2002).    We recognize, nonetheless,

that it is not practicable to eliminate the concept of testing

entirely from trial testimony.     The FSTs are used as means to

evaluate a defendant's ability to perform discrete tasks which

are correlated to skills required to safely drive a vehicle.

See Webster's New Universal Unabridged Dictionary 1951 (2003)

(defining "test" as, inter alia, "a set of questions, problems,

or the like, used as a means of evaluating the abilities,


     19
       Here, for example, a trooper testified at the motion
hearing that "the results of the [WAT and OLS] indicated that
Gerhardt was impaired." This testimony would not be admissible
at trial.
     20
       On cross-examination, defense counsel may challenge a
police officer's testimony concerning a defendant's performance
of an FST or any portion of an FST. See S.L. Jones, Drunk
Driving Defense, §§ 3.33-3.48 (2016-2017 ed.). See also id. at
§§ 3.49-3.54. We do not bar defense counsel from eliciting from
the officer his or her subjective evaluation of the defendant's
performance, but we stress that defense counsel makes this
strategic decision at his or her own peril, and opens the door
to redirect examination by the Commonwealth on the same topic.
                                                                      17


aptitudes, skills, or performance of an individual or group;

examination," and "a set of standardized questions, problems, or

tasks designed to elicit responses for use in measuring the

traits, capacities, or achievements of an individual").     An

officer administering the WAT, for example, assesses a

defendant's ability to take nine steps, walk heel-to-toe on a

straight line, turn around, and return in the same manner.       In

some sense, the officer thereby "tests" (measures, examines,

evaluates, assesses, or, at a minimum, observes) the driver's

physical balance and coordination, as well as his or her mental

ability to understand and follow directions and to perform

divided-attention tasks, albeit not in the same way that a

chemist in a laboratory tests a sample for the presence of a

particular substance.   In all circumstances, however, it must be

made clear to the fact finder that the WAT, the OLS, and the

other FSTs do not directly test marijuana impairment.     The FSTs

are a means of evaluating a defendant's balance, coordination,

and other skills specific to that test.   In addition, a witness

testifying to the performance of FSTs in the context of

marijuana intoxication should refer to a driver's performance on

"roadside assessments," so as not to suggest that they function

as scientific validation of a defendant's sobriety or

intoxication.
                                                                   18


     We emphasize as well another consequence of the lack of

consensus regarding the FSTs:   the fact that the FSTs cannot be

treated as scientific "tests" of impairment means that evidence

of performance on FSTs, alone, is not sufficient to support a

finding that a defendant's ability to drive safely was impaired

due to the consumption of marijuana, and the jury must be so

instructed.21

     c.   Lay testimony on the effects of marijuana.   We also are

asked whether a police officer may testify, without being

qualified as an expert, to the effects of marijuana consumption

and may offer an opinion that a defendant was intoxicated by

marijuana.   We conclude that an officer may not do so.

     "A lay opinion . . . is admissible only where it is

'(a) rationally based on the perception of the witness;

(b) helpful to a clear understanding of the witness's testimony

or the determination of a fact in issue; and (c) not based on

scientific, technical, or other specialized knowledge.'"

Commonwealth v. Canty, 466 Mass. 535, 541 (2013), quoting Mass.

G. Evid. § 701 (2013).   In the alcohol context, "a lay [officer]

. . . may offer his opinion regarding a defendant's level of

sobriety or intoxication but may not opine whether a defendant

operated a motor vehicle while under the influence of alcohol or

     21
       A model jury instruction regarding FSTs, to be used in
prosecutions for operating under the influence of marijuana, is
set forth in the Appendix.
                                                                   19


whether the defendant's consumption of alcohol diminished his

ability to operate a motor vehicle safely."   Canty, supra at

544, citing Commonwealth v. Jones, 464 Mass. 16, 17 n.1 (2012).

Such lay opinion testimony is proper because it is not based on

scientific, technical, or other specialized knowledge that would

require expert testimony, but, rather, lies within the realm of

common experience.   We long have observed that "[t]he 'effects

of liquor upon the minds and actions of men are well known to

everybody.'"   Commonwealth v. Wall, 469 Mass. 652, 671 (2014),

quoting Commonwealth v. Taylor, 263 Mass. 356, 362 (1928).      See

Canty, supra at 542, quoting Holton v. Boston Elevated Ry. Co.,

303 Mass. 242, 246 (1939) ("'the principal objective symptoms

[of alcohol intoxication] are so well known' that we consider

the lay opinion to have probative value").

    No such general knowledge exists, however, as to the

physical or mental effects of marijuana consumption, which vary

greatly amongst individuals.   On remand, the District Court

judge reported in his findings of fact, based on expert

testimony presented by both sides and numerous scientific

studies, as well as existing case law in Massachusetts, that

"[n]o studies have concluded that any specific characteristics

are routinely found in people who have used marijuana and were

impaired.   Manifestations of impairment may differ between

subjects who are under the influence of liquor and those who are
                                                                   20


under the influence of marijuana, depressants, or stimulant

substances.    The judge found further that some scientific

studies had identified "four prevalent physical characteristics

common among those who were determined to be cannabis-positive

drivers . . . These physical characteristics are red and/or

bloodshot eyes, a lack of convergence, eyelid tremors, and

drowsiness."    He determined, however, that no testimony admitted

at the Daubert-Lanigan hearing related these physical

characteristics "to an inference of impaired driving by reason

of marijuana use.    Further, no scientific studies validating

these specific physical characteristics as symptomatic of

impaired driving by reason of marijuana use were entered into

evidence."    Our review of the record confirms that the judge’s

findings regarding lay opinion evidence are supported by the

documentary evidence and in the studies submitted to us.

     Where there is no scientific consensus on what, if any,

physical characteristics indicate marijuana intoxication, no lay

opinion can be admissible as common knowledge or understanding

on that subject.    A lay witness may testify concerning a

defendant's observable appearance, behavior, and demeanor, but

may not offer an opinion as to the defendant's sobriety or

intoxication.22    See State v. Schories, 827 N.W.2d 659, 666 (Iowa


     22
       We caution the Commonwealth that "a prosecutor who
elicits from a police officer his or her special training or
                                                                     21


2013) (expert testimony preferred on cause of intoxication for

substances other than alcohol); State v. Noback, 309 Mont. 342,

346 (2002) ("we are not persuaded that lay people are

sufficiently knowledgeable about common symptoms of drug

consumption . . . to offer lay opinion testimony"); State v.

Bealor, 187 N.J. 574, 587 (2006) (court declined "to place lay

opinion testimony regarding marijuana intoxication on the same

footing as lay opinion testimony as to alcohol intoxication").

See also Commonwealth v. Sliech-Brodeur, 457 Mass. 300,

330 & n.43 (2010) (lay witness may not testify that individual

suffers from mental illness, but may testify to observed

behavior).

    With respect to the question of jurors' use of their own

common sense, we recognize that jurors are the ultimate arbiters

of the facts.   See Commonwealth v. Lykus, 367 Mass. 191, 197

(1975).   As a general rule, trial judges routinely instruct

jurors, and jurors are urged by counsel, "not [to] leave their

common sense outside the jury room."     See Commonwealth v.

Mutina, 366 Mass. 810, 820 (1975).     Jurors may use their common

sense in evaluating whether the Commonwealth introduced



expertise in ascertaining whether a person is intoxicated risks
transforming the police officer from a lay witness to an expert
witness on this issue, and the admissibility of any opinion
proffered on this issue may then be subject to the different
standard applied to expert witnesses." See Commonwealth v.
Canty, 466 Mass. 535, 541 n.5 (2013).
                                                                  22


sufficient evidence to satisfy its burden of proof.    See

Commonwealth v. Cole, 380 Mass. 30, 35-36 (1980) (in context of

criminal responsibility, jurors may rely on facts and

circumstances surrounding crime to determine whether

Commonwealth established defendant's sanity).    We rely on the

judge's limiting instructions to inform jurors about the proper

use of FST evidence.   See Commonwealth v. Jackson, 384 Mass.

572, 579 (1981).

    Conclusion.    We answer the reported questions as follows:

         1. "No." Police officers may not testify to the
    administration and results of FSTs as they do in operating
    under the influence of alcohol prosecutions. Police
    officers may testify to the administration of "roadside
    assessments" in the manner set forth in this opinion.

         2. "No." A lay witness may not offer an opinion that
    another person is "high" on marijuana.

         3. "Yes." A police officer may testify to observed
    physical characteristics of the driver such as blood shot
    eyes, drowsiness, and lack of coordination. The officer is
    not permitted to offer an opinion that these
    characteristics mean that the driver is under the influence
    of marijuana.

         4. "Yes." Jurors are permitted to utilize their
    common sense in assessing trial evidence.

    The case is remanded to the District Court for further

proceedings consistent with this opinion.

                                   So ordered.
                            Appendix.


Model Jury Instruction Regarding Roadside Assessments for Use in
   Prosecutions for Operating Under the Influence of Marijuana

     You heard testimony in this case that the defendant, at the
request of a police officer, performed or attempted to perform
various roadside assessments, such as [Here outline the nature
of the evidence, e.g., walking a straight line, balancing on one
foot]. These roadside assessments are not scientific tests of
impairment by marijuana use. A person may have difficulty
performing these tasks for many reasons unrelated to the
consumption of marijuana.

     It is for you to decide if the defendant's performance on
these roadside assessments indicate that his [her] ability to
operate a motor vehicle safely was impaired. You may consider
this evidence solely as it relates to the defendant's balance,
coordination, mental clarity, ability to retain and follow
directions, ability to perform tasks requiring divided
attention, and other skills you may find are relevant to the
safe operation of a motor vehicle.

     It is for you to determine how much, if any, weight to give
the roadside assessments. In making your determination, you may
consider what the officer asked the defendant to do, the
circumstances under which they were given and performed, and all
of the other evidence in this case.

     Finally, evidence of how a defendant performed in roadside
assessments, standing alone, is never enough to convict a
defendant of operating under the influence of marijuana.
