In United States v. Bailey, 622 F.3d 1, 393 U.S. App. D.C. 131 (D.C. Cir. 2010), an officer was working undercover when he attempted to make a purchase of cocaine from a drug dealer.
While waiting to complete the purchase, the officer saw the defendant go into the alley behind the drug dealer's restaurant. Id. at 3.
Shortly thereafter, the drug dealer's supplier drove his car into the alley behind the drug dealer's restaurant, stopping by a storage shed where the officer had previously bought drugs from the drug dealer. Id.
Thirty seconds later, the defendant drove his car into the alley and parked it parallel to the drug supplier's car. Id.
A few minutes later, the supplier drove out of the alley and the officer made his drug purchase from the drug dealer. Id. Shortly thereafter, the defendant was stopped by another officer. Id.
The D.C. Circuit held that the officer had a reasonable suspicion that the defendant was engaged in criminal activity because the officers "observed and recorded the defendant and the drug dealer talking and walking together at the time and place the drug dealer was arranging to sell drugs to the undercover officer." Id. at 7.