My question involves a consumer law issue in the State of: California

Is it legal for Wal-Mart's receipt checkers to demand to see my receipt at the door after I purchase an item?

Can they detain me until I provide the receipt?

Sure its super easy to pull the receipt out and show them but it really bothers me that they will not allow me to leave unless I stop, put down my bags, find my receipt and then show it.

Dave