there's no law against (something)
It is perfectly acceptable to (do something). Typically said in response to criticism of or a warning against some action. Why shouldn't I try to haggle with the waitress? There's no law against it. There's no law against returning something I've already worn. Stop trying to make me feel bad about it.
there's no law against it
used in spoken English to assert that you are doing nothing wrong, especially in response to an actual or implied criticism. informal