can a confidential informant, who has a conviction for making false reports to law enforcement.

Yes.  Police may use informants with criminal records in undercover activities , such as controlled buys of drugs, guns or other contraband. The informant may be paid with money, or with promises for lenient treatment or immunity from prosecution for his own misdeeds. If the informant was directly involved  in the  controlled purchase of the firearm, for example, if you handed it to him and he paid you for it, or he was “an eye and ear witness” to the sale, and he is going to be a witness at trial, the prosecution will have to disclose his past criminal history before trial. The defense will bring his past record to the attention of the jury during its cross-examination of the informant, and argue to the jury in closing that he should not be believed.  The jury will make the ultimate decision on the informant’s credibility. In many jurisdictions, juries are instructed that the testimony of an informant should be viewed with greater caution than that of an ordinary witness. Some jurisdictions use an instruction that advises jurors that if the informant’s testimony is not supported by other evidence, they should not convict unless they believe the informant’s testimony  beyond a reasonable doubt.Thus, it is critical to examine any evidence police have to support the charge besides the informant’s testimony.  Exposing the informant’s past history of lying may not be enough for an acquittal if there is substantial other evidence supporting his account.  In controlled buys, police may wire the informant to record the transaction, photocopy the serial numbers of the currency provided to him to buy the gun, and search the informant immediately before and after the buy, to establish that the gun or money was not obtained  elsewhere. Such additional evidence allows the prosecution to argue the case does not hinge solely on the informant’s testimony. I recommend you consult with an experienced criminal defense attorney in your jurisdiction, who will be familiar with the practices used by  local law enforcement in controlled buys. He or she can listen to your account of what transpired, review the police reports, and advise you as to potential defenses, including affirmative defenses, such as entrapment.  Jeralyn Merritt, Ask a Lawyer Panelist Since 1998