human sacrifices, child sex, etc
You aren't the first one to bring up this idea. The things you mentioned are illegal whether done in the name of religion or for some other reason. OTOH, nothing that JW's teach violate generally applicable laws in the U.S. "Brainwashing," as you call it, or "religious instruction" as they would characterize it, is not illegal. As anony mous said, you are free to join and leave even if you might not like the terms. Shunning is not illegal either. Congress couldn't do anything, and wouldn't want to in any event. There are no political points to be gained by going after religious groups (at least non-Muslim religious groups). Look at how much more wacky and dangerous Scientologists are, and how much has been done to "investigate" or "regulate" them. That should tell you all you need to know about how far anyone would get trying to get the government to go after them.