>What about the groups that kill people for money, or extort 'protection money', or groups that rob banks? Unless you want to make murder, arson and theft legal

>What about the groups that kill people for money, or extort 'protection money', or groups that rob banks? Unless you want to make murder, arson and theft legal, you need to go undercover in these groups. You watch too many movies. Such groups are extraordinarily rare, and it's even rarer that they'd be around long enough to actually infiltrate. The only real examples are organized crime, and almost universally a "man inside" is not an undercover cop, but a former member who's changed sides.