Guilt by association is not a valid theory of legal liability. After all, except in limited circumstances, there is an almost constitutional right to associate with others. The U.S. Constitution allows freedom of speech, which necessarily bars prosecution for associating with others (NAACP v. Alabama (1958), a U.S. Supreme Court case). So can someone be prosecuted for being present while others are using drugs? If so, under what circumstances? To read about this issue, click on the following link.