Since Roe v. Wade, abortion has continued to be a divisive political issue in the United States. In contrast, it has remained primarily a medical issue in Britain and Canada despite the countries’ shared heritage. This book looks beyond simplistic cultural or religious explanations to find out why abortion politics and policies differ so dramatically in these otherwise similar countries. It argues that political institutions are the key. In the United States, federalism, judicial review, and a private healthcare system contributed to the public definition of abortion as an individual right rather than a medical necessity. Meanwhile, the book explains, the porous structure of American political parties gave pro-choice and pro-life groups the opportunity to move the issue onto the political agenda.