...and stick almost exclusively to it?
According to Collins Dictionary:
A loophole in the law is a small mistake which allows people to do something that would otherwise be illegal.
The Grammarist notes that:
Interestingly, the word loophole goes back to the sixteenth century and refers to an architectural feature. In castles of the time, narrow slits were built into the walls where archers could shoot at attackers. These narrow slits were known as loopholes, most probably derived from the Dutch word lûpen meaning to watch.
The term loophole came into use in the seventeenth century in a figurative sense to mean a small opening or a outlet of escape.
How and when did loophole become associated with law?
How old is the expression Every law has its loophole?