One who participates in a crime as a decoy to apprehend the actual criminal is not criminally liable.
Wilson (Defendant/Appellant) and Pierce spent the night drinking and fraternizing in Sterling, Colorado on February 18, 1938 when Wilson noticed that his watch had gone missing. Wilson accused Pierce of stealing the watch, and heated discussion ensued. After a time, Pierce bragged about the burglaries he had committed in the past and Wilson sought to entrap him. Wilson suggested breaking into Hecker Brother’s Drugstore, and Pierce readily agreed. When they arrived, Wilson boosted Pierce through the front transom and then immediately ran to phone the police to inform them that Pierce was inside the Hecker Brother’s Drugstore. When the police arrived, Pierce escaped through the back door and was later tracked down with Wilson’s help. Both men were arrested and charged. At trial, a jury instruction was delivered which stated that: “"One may not participate in the commission of a felony and then obtain immunity from punishment on the ground that he was a mere detective or spy. One who attempts to detect the commission of crime in others must himself stop short of lending assistance, or participation in the commission of the crime." Wilson was convicted and an appeal followed.
Is participation in a felony as a feigned accomplice for purposes of police entrapment sufficient to avoid criminal liability?
While detectives, when acting as decoys, may apparently provoke the crime, the essential element of dolus, or malicious determination to violate the law, is wanting in their case. And it is only the formal, and not the substantive, part of the crime that they provoke. They provoke, for instance, in larceny, the asportation of the goods, but not the ultimate loss by the owner. They may be actuated by the most unworthy of motives, but the animus furandi in larcency is not imputable to them; and it is in larcenous cases or cheats that they are chiefly employed. It may be that the jury in the instant case placed more stress on the motives that actuated Wilson in his participation in the transaction than they did on the necessity of determining his felonious intent under the circumstances. . . the giving of [the jury instruction] constituted prejudicial error.