Researchers at University of Massachusetts in concert with Norwegian have discovered male contraception pill to be produced. They have found a way to stop motility of the flagella. It's a way to turn off the tail, no side effects, and reversible.
http://www.boston.com/news/globe/health_science/articles/2005/01/31/way_seen_to_male_birth_control_pill/
http://www.boston.com/news/globe/health_science/articles/2005/01/31/way_seen_to_male_birth_control_pill/