Yes? How does it do this rather than simply prevent implantation?
Boxer is hoping for a miracle drug maybe a Viagra/LSD combo so someone might go for her...
It creates a chemical environment that makes fertilization impossible. Fertilization can take place up to a day after intercourse. It uses a synthetic version of the same chemical reaction the ovum excretes after fertilization that prevents more than one sperm from fertilizing an egg.
So, they never get together.
They use this stuff in the ERs of Catholic hospitals for rape victims. My guess is that they have the ethics down pretty well.