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   STATE OF CONNECTICUT v. ROBERT ELECK
                (SC 18876)
 Rogers, C. J., and Palmer, Zarella, Eveleigh, McDonald, Espinosa and
                            Vertefeuille, Js.
    Argued October 29, 2013—officially released October 21, 2014

  William B. Westcott, assigned counsel, for the appel-
lant (defendant).
  Timothy F. Costello, assistant state’s attorney, with
whom, on the brief, were David I. Cohen, state’s attor-
ney, and Joseph C. Valdes, senior assistant state’s attor-
ney, for the appellee (state).
                         Opinion

   EVELEIGH, J. The defendant, Robert Eleck, appeals
from the judgment of the Appellate Court, which
affirmed the judgment of conviction of assault in the
first degree by means of a dangerous instrument in
violation of General Statutes § 53a-59 (a) (1) rendered
by the trial court following a jury trial. See State v.
Eleck, 130 Conn. App. 632, 633, 23 A.3d 818 (2011). The
sole claim raised by the defendant in this appeal is that
the Appellate Court improperly affirmed the judgment
of the trial court on the ground that evidence of an
online conversation proffered by the defendant to
impeach one of the state’s witnesses was not properly
authenticated and was therefore inadmissible. Assum-
ing, without deciding, that it was improper for the trial
court to exclude the proffered evidence, there was no
harm. Therefore, we affirm, on other grounds, the judg-
ment of the Appellate Court.
   The opinion of the Appellate Court sets forth the
following relevant facts and procedural history. ‘‘The
defendant attended a party at 16 Charles Street in Nor-
walk in the early morning hours of December 9, 2007.
All of the approximately twenty teens and young adults
who attended were consuming alcoholic beverages, and
many were intoxicated. While inside the house, the
defendant was involved in at least two verbal confronta-
tions with one guest, Matthew Peacock. The defendant
also conversed on several occasions with another guest,
Simone Judway. Shortly after 2:30 a.m., outside the
house, the defendant and Peacock engaged in a physical
altercation that included punching and grappling. Three
other guests, including Zachary Finch, joined the fight
to help Peacock. When the combatants were separated,
both Peacock and Finch discovered that they had suf-
fered stab wounds.
   ‘‘The defendant subsequently was arrested and
charged with assault in the first degree with a dangerous
instrument in violation of § 53a-59 (a) (1) in connection
with the injury to Peacock and assault in the second
degree in violation of General Statutes § 53a-60 (a) (2)
in connection with the injury to Finch. Following a trial
to the jury, the defendant was convicted of assault in
the first degree regarding the assault on Peacock and
acquitted of assaulting Finch. Because the defendant’s
assault conviction involved the use of a dangerous
instrument, he faced a mandatory minimum sentence of
five years. He was, in fact, sentenced to the mandatory
minimum sentence of five years incarceration with an
additional ten years of special parole.’’ Id., 633–34.
  The defendant appealed from the trial court’s judg-
ment of conviction to the Appellate Court, claiming,
inter alia, that the trial court improperly ruled that a
printed copy of an online conversation between the
defendant and a person utilizing Judway’s Facebook
account,1 which the defendant attempted to submit into
evidence for the purpose of impeaching Judway’s testi-
mony, had not been properly authenticated.2 Id., 634.
The Appellate Court disagreed with the defendant and,
accordingly, concluded that the trial court had not
abused its discretion in declining to admit the document
into evidence. Id., 644. This appeal followed.3
   The opinion of the Appellate Court reveals additional
facts and procedural history that are relevant to the
defendant’s claim. ‘‘As a witness for the state, Judway
offered key testimony that, prior to the physical alterca-
tion, the defendant had told her that ‘if anyone messes
with me tonight, I am going to stab them.’ Subsequently,
during cross-examination, defense counsel sought to
impeach Judway’s credibility by asking her whether she
had spoken with the defendant in person since the
incident. She responded that she had seen the defendant
in public but had not spoken to him in person, by tele-
phone or by computer. Defense counsel then showed
Judway a printout purporting to show an exchange of
electronic messages between the defendant’s Facebook
account and another account under the user name
‘Simone Danielle.’ Judway identified the user name as
her own, but denied sending the messages to the defen-
dant. She also testified that someone had ‘hacked’ into
her Facebook account and changed her password ‘two
[to] three weeks’ ago such that she had been unable to
access it subsequently.
   ‘‘On the following day, during the defendant’s testi-
mony, his counsel offered into evidence the defendant’s
Facebook printout containing messages purportedly
from Judway. The state objected on the grounds that
the authorship of the messages could not be authenti-
cated and [thus] the document was irrelevant. In
response, to authenticate the document, the defendant
testified that he downloaded and printed the exchange
of messages directly from his own computer. He also
advanced testimony that he recognized the user name,
‘Simone Danielle,’ as belonging to Judway because she
had added him as a Facebook ‘friend’ a short time before
he received the message. He testified that the ‘Simone
Danielle’ profile contained photographs and other
entries identifying Judway as the holder of that account.
Finally, he testified that when he logged in to his Face-
book account after the previous day’s testimony, user
‘Simone Danielle’ had removed him from her list of
Facebook ‘friends.’ The defendant’s counsel then
argued that based on this testimony and Judway’s iden-
tification of her user name, there was a sufficient foun-
dation to admit the document for the jury’s
consideration.’’ (Footnotes omitted.) Id., 635–36.
  As set forth by the Appellate Court in a footnote,
the printout of the online conversation between the
defendant and ‘‘Simone Danielle’’ proffered by the
defendant consisted of the following:4
   ‘‘Simone Danielle: Hey I saw you the other day and
I just want to say nice bike.
  ‘‘[The Defendant]: why would you wanna talk to me
  ‘‘Simone Danielle: I’m just saying that you have a nice
bike that’s all. The past is the past.
  ‘‘[The Defendant]: yup thanks
 ‘‘Simone Danielle: No problems.’’ (Internal quotation
marks omitted.) Id., 635 n.2.
   As noted by the Appellate Court, ‘‘[t]he [trial] court
. . . sustained the state’s objection on the ground that
the defendant had not authenticated that the messages
were written by Judway herself.’’ Id., 636.
  The defendant does not claim that the trial court’s
refusal to admit the proffered document infringed on
any of his constitutional rights. Instead, the defendant
claims that the ruling is evidentiary in nature.5
   Regardless of the defendants claims, assuming, with-
out deciding, that it was improper to exclude the prof-
fered evidence, we now examine whether the exclusion
was harmful. ‘‘When an improper evidentiary ruling is
not constitutional in nature, the defendant bears the
burden of demonstrating that the error was harmful.
. . . [W]hether [an improper ruling] is harmless in a
particular case depends upon a number of factors, such
as the importance of the witness’ testimony in the prose-
cution’s case, whether the testimony was cumulative,
the presence or absence of evidence corroborating or
contradicting the testimony of the witness on material
points, the extent of cross-examination otherwise per-
mitted, and, of course, the overall strength of the prose-
cution’s case. . . . Most importantly, we must examine
the impact of the . . . evidence on the trier of fact and
the result of the trial. . . . [T]he proper standard for
determining whether an erroneous evidentiary ruling
is harmless should be whether the jury’s verdict was
substantially swayed by the error. . . . Accordingly, a
nonconstitutional error is harmless when an appellate
court has a fair assurance that the error did not substan-
tially affect the verdict.’’ (Internal quotation marks omit-
ted.) State v. Favoccia, 306 Conn. 770, 808–809, 51 A.3d
1002 (2012). In the present case, we conclude that,
assuming, without deciding, that the exclusion of the
proffered evidence was improper, the ruling was
harmless.
   The defendant argues that the evidentiary error was
improper because the online conversation impeached
Judway. Specifically, the defendant claims that Judway
denied having any contact with the defendant between
the night of the assault and the day of trial and that
this conversation impeached that testimony. The defen-
dant’s position is that the failure to impeach Judway
likely affected the jury’s verdict because Judway’s testi-
mony suggested that the defendant was prepared to
stab anyone who ‘‘messes with’’ him, which suggested
premeditation on the part of the defendant. In addition,
the defendant notes that both the state, during its clos-
ing argument, and Detective James O’Leary, of the Nor-
walk Police Department, the officer who interviewed
the witnesses in this case, believed that Judway was
the most reliable witness because she did not smell of
alcohol and wrote out her own statement.
   The state argues that any impropriety was harmless.
The state claims that its case against the defendant was
strong, as multiple witnesses identified the defendant
as the person who initiated the physical altercation with
Peacock, at least two witnesses saw the defendant wrap
Peacock in a bear hug, another saw the defendant hold-
ing a knife at the end of the fight, and several witnesses
observed that Peacock was bleeding soon after the con-
frontation with the defendant. The state also notes that
the defendant admitted to using a knife during the fight.
Further, the state claims, the substance of the conversa-
tion between Judway and the defendant did not touch
on the details of the case or Judway’s impending testi-
mony and, thus, admission of the conversation would
likely have little impact on the jury’s determination on
Judway’s credibility. Finally, the state notes that the
defendant presented testimony to the jury indicating
that he had received messages from a Facebook
account maintained by Judway and that, during closing
arguments, the defendant used this testimony to attack
Judway’s credibility. It is the state’s position that the
introduction of the printout of the Facebook conversa-
tion between the defendant and Judway would, thus,
have been very unlikely to have had a substantial impact
on the jury’s verdict.
  We agree with the state. The defendant has not shown
that the exclusion of the proffered evidence had a sub-
stantial impact on the jury’s verdict. In addition, the
state’s case was strong. Numerous witnesses not only
identified the defendant as the person who initiated the
contact with Peacock, but also noticed after the contact
that Peacock was bleeding. Further, the defendant
admitted using a knife during the fight. Given that the
defendant presented evidence in the form of his own
testimony that he was contacted by Judway and argued
during closing argument that her denial of authorship
should be taken into account when judging Judway’s
credibility, it is doubtful that the admission of the print-
out would have had any additional impact. We conclude,
therefore, that assuming, without deciding, that there
was any evidentiary impropriety, the ruling was
harmless.
      The judgment of the Appellate Court is affirmed.
      In this opinion the other justices concurred.
  1
   Facebook is ‘‘a free, web-based social networking site with over 153
million members in the United States. . . . To join Facebook, a user must
provide his or her name, age, gender, and a valid e-mail address, and agree
to Facebook’s terms of service. . . . Once registered, a member receives
a [p]rofile page, may upload a profile photo representing him or herself,
and may establish connections with other members by approving them as
Facebook [f]riends.’’ (Citations omitted; internal quotation marks omitted.)
Fraley v. Facebook, Inc., 830 F. Supp. 2d 785, 791 (N.D. Cal. 2011).
   2
     The defendant also claimed that this state’s statutory sentencing scheme,
which mandated that the defendant receive a nonsuspendable sentence of
five years, was unconstitutional. State v. Eleck, supra, 130 Conn. App. 644–45.
The Appellate Court declined to review this claim after concluding that the
issue was governed by its previous decision in State v. Schultz, 100 Conn.
App. 709, 726–29, 921 A.2d 595, cert. denied, 282 Conn. 926, 926 A.2d 668
(2007). State v. Eleck, supra, 645. This claim is not, however, at issue in the
present appeal. See footnote 3 of this opinion.
   3
     We granted the defendant’s petition for certification to appeal limited
to the following question: ‘‘Did the Appellate Court properly determine that
the trial court did not abuse its discretion in concluding that Facebook
messages purportedly sent by a witness were inadmissible because they
lacked sufficient authentication?’’ State v. Eleck, 302 Conn. 945, 30 A.3d 2
(2011). The defendant did not petition this court to review the Appellate
Court’s decision not to review his constitutional claim. See footnote 2 of
this opinion.
   4
     The conversation is presented without modification and, thus, contains
both grammatical and spelling errors.
   5
     Whether the same rules that apply for the authentication of documents
should also apply to electronic data, in view of our ruling, remains an open
question. We note that Judge Bishop currently heads a committee regarding
the Connecticut Code of Evidence. We would urge that committee to con-
sider this issue.
