As digital books have become a larger part of book-selling revenue, the issue of who owns the digital rights to older titles has become increasingly contentious because many older publishing contracts don't specify them.

WSJ: Amazon Loses E-Book Deal

The fate of the federal health care law currently before the Supreme Court is likely in the hands of Justice Anthony Kennedy, who has already cast the swing vote in a number of contentious cases over the past decade.

FORBES: Obamacare's Fate Lies In Anthony Kennedy's Hands: System Failure

Among the papabili from these areas of the world is Ghana's Cardinal Peter Kodwo Appiah Turkson, 64, who has won praise for addressing some of the church's most contentious positions, including its opposition to distributing condoms to curb HIV transmission.

WSJ: Contenders in Line to be Pope

So the politics of who is and who is not allowed to enter this country, and on what terms, has always been contentious.

WHITEHOUSE: President Obama on Comprehensive Immigration Reform