Law Question - Can I be held responsible for injury to a thief?

I'm going to give this one more shot, but if someone steals my yogurt out of the communal fridge again, its replacement will include a lot of laxatives. I cannot live without my yogurt and granola in the morning. I promise retaliation.

You probably don't care, but I thought you might like to revel in the fact that you only share a refrigerator with your family.