My question involves a traffic ticket from the state of: Texas

My uncle drove on a street in Houston, Texas. The street's limit were 45 miles per hour (MPH) when the police pulled him over and told him the miles that he drove is over, which were 48 MPH but when the police printed out a paper from a laser speed gun (whatever you call) the MPH that he saw were 50 MPH. He admitted that was his fault but when he asked the police about the miles that he saw on a paper printed from the laser speed gun were 50 MPH instead of 48 MPH, the police told him go to the court and ask them!!! What!!! How come? Can you please explain for me what to do in this situation? thank you.