In the city's toughest neighborhoods, narcotics officers routinely bust mini-marts and bodegas for selling tiny ziplock plastic bags.
Police consider the bags to be drug paraphernalia. But many store owners say they bought the bags legally from tobacco wholesalers and other distributors and thought they could sell them.
At issue is whether the buyer is using the bags for drugs or for legitimate items like coins, jewelry, stamps and small amounts of tobacco.
"The question is whether the item is for a legal function or an illegal function," said Tennessee-based lawyer Robert T. Vaughn, an expert on drug-paraphernalia laws.
Under Pennsylvania law, selling the bags is a crime if the shop owner "knows or should reasonably know" that the buyer intends to use them for drugs.