Via quaoar, the Pope has strongly backed Catholic clergy in their decision to excommunicate politicians who support choice:

Speaking to reporters on his way to Brazil, Pope Benedict has backed Mexican bishops who have threatened excommunication for parliamentarians who voted to legalise abortion in Mexico City. . . . "Yes, this excommunication was not an arbitrary one but is allowed by Canon (church) law which says that the killing of an innocent child is incompatible with receiving communion, which is receiving the body of Christ," he said.

Passing a law giving women the right to choose is not having an abortion so the logic escapes me here. I guess there is some accomplice theory but I have to wonder, what about laws allowing for birth control, also viewed as a grave sin by the Catholic Church:

the Catholic church also teaches that many methods of contraception would be a violation of natural law and therefore morally evil because they interfere with the natural processes such as condoms, diaphragms, other barrier methods, spermicides, intrauterine devices, chemical methods such as pills, patches, injections, and implants. Likewise the Catholic Church views surgical sterilization methods as being opposed to natural law because they prevent the possibility of conception.

Some politicians in the world voted to allow birth control. Are they going to be excommunicated?

And what about remarriage?