Which branch of government has the power to impeach supreme court justices?

The Legislative branch.

Impeachment is a two-step process involving both houses of Congress.

well it depends i think people around the world are coming around to gay marriage. but if you are talking abortion then wow, so much to talk about. such as men thinking they have the right to choose if women can, the fact there are health concerns if the women can't get one, and many more arguments to discuss. so i would definitely say abortion would be a much more interesting topic.

answer; they both highlight the power of the situation in determining behavior;