There’s no law against something

Pro Tip 1/3

This phrase is casual and more commonly used in spoken rather than formal written English.

Sure, you can wear pajamas to the store—there's no law against it.

Pro Tip 2/3

Using the phrase can suggest that an action, while not illegal, may still be frowned upon.

He double-dips his chips, and while there's no law against that, people find it gross.

Pro Tip 3/3

Can be used sarcastically to imply that something is permissible but not necessarily wise or considerate.

There's no law against eating smelly food on the bus, but you'll make enemies.