A federal judge blocked a defense expert from giving most of his proposed testimony at the trial of a lawsuit accusing a police sergeant of using excessive force when he shot a driver to death.In a written opinion, U.S. District Judge Iain D. Johnston of the Northern District of Illinois held Dale Mann of Engineering Systems Inc. does not qualify as an expert in all the subjects covered in his report on Nathaniel Edwards’ shooting.Mann prepared the report for the city of Rock Falls and Sgt. Jonathan Cater, the defendants …