Over 20 years ago, New Jersey’s Supreme Court concluded that expert opinions maybe received into evidence in cases involving drug transactions.  The underlying philosophy of the court's.  Ruling was that the nature of drug transactions are beyond the understanding of the average citizen, and to that extent, expert testimony may assist a jurors in their deliberation.  Over the years, the Court has allowed experts to testify about; (A) the difference between drugs that are possess with an intent to distribute for those that are possessed for personal use; (B) the roles and importance of the roles played by the various actors in a drug transaction; (C) the nuances of drug transactions, including the purpose of packaging, the use of juveniles as quote mules" etc.

On the other hand, the Court has noted that if the transaction is "straightforward" in nature, i.e., and hand-to-hand exchange of money and drugs, an expert witness is not required and should not be subject of opinion evidence. Recently, the court addressed the question of whether and to what extent a lay witness testify about his opinion of a drug transaction.  In that case, a surveillance team of local law enforcement agents observe the defendant involved in two furtive transactions which resulted in his arrest and search of the vehicle that produced packages of heroin and cocaine.

At trial, the prosecutor sought to establish from one of the investigating officers, who was not an expert in drug transactions,  an opinion as to whether his observations led him to believe that the transaction was drug-related.  When the defendant’s attorney objected, the prosecutor sought to justify the question by contending it was appropriate under the lay witness opinion rule. The trial court agreed with this prosecutor and the defendant was ultimately convicted.  The conviction was confirmed on appeal.  The issue before the Supreme Court was whether the lay witness opinion rule authorize the question. In conviction, the court concluded that the transaction was not beyond the understanding of the jurors; that the police officer improperly referenced the defendant in the hypothetical question; that the question and the answer was an expression of the witnesses believe that the defendant was guilty; and that the prosecutor’s preliminary questions about the officers training and education could have convince a jury that testimony was grounded upon an expert's opinion.