215 F.3d 750 (7th Cir. 2000)
United States of America,    Plaintiff-Appellee,v.Trampas Austin,    Defendant-Appellant.In the  United States Court of Appeals  For the Seventh Circuit
No. 99-3766
Argued May 10, 2000
Decided June 15, 2000

Appeal from the United States District Court  for the Southern District of Illinois.  No. 97-40068-JPG--J. Phil Gilbert, Chief Judge.
Before Easterbrook, Ripple, and Rovner,  Circuit Judges.
Easterbrook, Circuit Judge.


1
An indictment  charged 14 persons with manufacturing and  distributing methamphetamine. Twelve  pleaded guilty, and some of these  testified against the two who stood  trial. Trampas Austin, one of these two,  now appeals from his conviction and 120-  month sentence.


2
All of the testifying participants in  this drug ring were users of their own  product. Counsel elicited this (which the  witnesses readily admitted) and the fact  that each witness had received or  expected some reward for cooperating with  the prosecution. Defense counsel asked  the jurors to discount this testimony  because of the witnesses' status as drug  users and their bargains with the  prosecution. He also asked the judge to  reinforce that argument with this  instruction:


3
If a witness who has cooperated with  the government is a user of  narcotics, there are reasons his or  her testimony should be considered  with great care. A regular user of  narcotics has a constant need for a  supply of drugs and for money to  support his or her habit and also  may have an abnormal fear of  imprisonment in which the supply of  drugs might be cut off.  Additionally, a witness who was  under the influence of marijuana,  methamphetamine or alcohol at the  time of a particular event may have  impaired recollection of that which  occurred during that event. These  are special circumstances which you  may consider in weighing testimony  of this kind. Of course, you may  give the testimony such weight as  you think proper after considering  all relevant circumstances.    But the judge declined to give this  instruction, observing that the witnesses  were not meth users at the time of trial  and thus did not need money to buy drugs  or fear the consequences of imprisonment  (which would cause withdrawal). Indeed,  six of the witnesses were in prison by  the time of Austin's trial and therefore  already had endured whatever ill effects  interruption of their drug consumption  could produce. Although the judge thought  an addict-informant instruction  inadvisable, he did give an informant  instruction, drawn from Instruction 3.13  of the Pattern Criminal Federal Jury  Instructions for the Seventh Circuit  (1998), telling the jury that the  testimony of any cooperating witness  should be "considered with caution and  great care."


4
Austin's proposed instruction told the  jury to receive the testimony of drug-  using informants "with great care." The  judge told the jury to use "caution and  great care" when considering the  testimony of these witnesses. What then  is Austin's beef? The instruction the  judge gave left out the reasons in  Austin's proposal. Lack of reasons is a  possible problem with skeletal cautionary  instructions, see United States v. Cook,  102 F.3d 249 (7th Cir. 1996), because the  practical meaning of "caution and great  care" depends on just why the jurors are  supposed to exercise care. What, in  particular, are they to look for when  deciding whether given testimony should  be accepted or discarded? Guidance on  this subject is the principal reason for  giving a cautionary instruction yet was  missing from the language the district  judge selected. But whether additional  guidance is needed is a subject that the  district judge knows best, and on which  appellate review is correspondingly  deferential. See United States v.  Yarbough, 55 F.3d 280, 284 (7th Cir.  1995); United States v. Manganellis, 864  F.2d 528, 544 (7th Cir. 1988). This court  has never reversed a district judge for  omitting advice of the sort Austin wanted  the instruction to provide, and this case  shows why.


5
Instructions lifted from pattern books,  as this was, often are misfits for the  events brought out at trial. As the  district judge observed, the witnesses  were not drug users at the time of trial  and did not need cash to feed their  habits. Those already in prison did not  especially fear withdrawal; they had  experienced it already, so there was no  risk that they would tailor their  testimony to curtail that risk. The only  advice that applied to these witnesses  was the statement that "a witness who was  under the influence of marijuana,  methamphetamine or alcohol at the time of  a particular event may have impaired  recollection of that which occurred  during that event." This purports to be a  statement of fact, and judges may be able  to simplify trials (and improve the  accuracy of deliberations) by informing  jurors about scientific knowledge that  jurors do not already have. See United  States v. Hall, 165 F.3d 1095, 1118-20  (7th Cir. 1999) (concurring opinion). But  is the proposition accurate? The  appellate briefs are unenlightening on  the subject. If accurate, does it apply  to these witnesses? An impaired memory  differs from a deluded mind. These  witnesses were not bystanders whose  ability to perceive events may have been  clouded by drugs; they claimed to be  participants in a long-running criminal  organization, and we have not been given  any reason to believe that using  methamphetamine can cause a person to  fantasize elaborate details like those  the witnesses provided to this jury. So  the proposed instruction could have done  more to mislead than to inform jurors  about the value of the testimony they  heard.


6
When circumstances warrant, a defendant  is entitled to "careful instructions"  about the credibility of informants, see On Lee v. United States, 343 U.S. 747,  757 (1952), but this proposed instruction  did not meet that description. The  district judge was entitled to leave the  subject to argument by counsel;  Instruction 3.13 added whatever extra may  have been called for. Cook, 102 F.3d at  252-54.

Affirmed
