Growing numbers of people are flocking to U.S. churches that center their practice around a bitter psychedelic tea known as ayahuasca. Organizers and their legal advisers argue a 2006 Supreme Court ruling protects them from prosecution and participants say they are taking part in a religious service. Some experts raise concerns that the benefits of ayahuasca haven’t been well studied. Many who attend the ceremonies, which can last for days, argue their experience on the illegal substance brings them closer to God than they ever felt at traditional religious services. Surveys have also found many come away feeling better afterwards, with some saying it helped with depression and problems with risky substance use.