On the wrong side of the law
Definition 1 of 2
Pro Tip 1/3Negative connotation
This phrase implies a poor judgment or choice, casting a shadow on one's character. 
She never imagined her brother would be on the wrong side of the law.
Pro Tip 2/3Legal trouble
Use when someone is actually in trouble with the law, not just behaving badly. 
Caught shoplifting, he was now firmly on the wrong side of the law.
Pro Tip 3/3Context Matters
The phrase is often used in news or stories about crime and justice. 
The once respected businessman found himself on the wrong side of the law.