More states are mandating how gun owners store their firearms at home, with lawmakers citing child safety as a primary driver, as well as keeping firearms out of the hands of potential school shooters and other violent criminals.

Stand Your Ground laws allow you to defend yourself with force — even deadly force — without requiring you to first try to run away. But here’s the catch: not every state gives you that protection.

Carrying a gun is supposed to make you more prepared—not set you up for legal trouble. But you have to know the rules, ...