Study finds possible chemical route to creating male birth control pill.a molecule called JQ₁ successfully inhibited the production of sperm in laboratory mice. The mice were rendered infertile and stayed that way for as long as they were injected with the drug. However, the effects of JQ₁ were also found to be easily reversible; once the mice stopped receiving daily dosages, their sperm levels returned to normal.
This speaks about a few future methods but I like it specifically for the male injection. It is stated that it will be 100% effective, so it would have a perfect use percentage of course. The only disadvantage I could see would be pain being that its injected into the penis (sorry guys). Most likely a prescription is needed being that this would have to be administered by a doctor (unless you trust some someone else with a needle to your penis).