A non-hormonal, reversible and non-toxic male birth control could be a step closer, with scientists successfully targeting a protein that's crucial in making fertile sperm. Knocking this protein out for a period of time would give men control over their protection window, much like oral…
RISUG is a technique by which a polymer with specific electrical properties is injected into the vas deferens. This polymer messes up the flagella on sperm that pass nearby. Since “nearby” is a distance larger than the radius of the vas deferens, this means all sperm passing through get their flagellum screwed up, can no longer swim, and is therefore immotile.
It makes the man essentially sterile, until he wants to reverse the effect at which point a second injection simply washes the original polymer layer off the inner lining.