This was the ruling theory of the 1950s and 1960s.

ECONOMIST: 20th-century art

If no party wins a clear victory, and is forced to ally with other parties to form a ruling coalition, the group could, in theory, ask Mr. Monti to return as prime minister.

WSJ: Scandals Rain on Berlusconi's Party

He says the Supreme Court ruling doesn't provide a principle or a theory to help judges or lawmakers figure out what's constitutional and what's not.

NPR: NRA Eyes More Targets After D.C. Gun-Ban Win

The ruling is a powerful rebuke of the so-called cy pres doctrine, a legal theory that has sprung up, despite dubious academic credentials, to deal with an intractable problem with class actions: Unclaimed funds.

FORBES: Court Rejects AOL Settlement Over Questionable Charity Awards

The revolution of 1789 in theory made the people sovereign yet in practice left power in the hands of an elite ruling in the people's name.

ECONOMIST: Eva Joly, France’s elite-hunting magistrate | The

There is a controversial theory put forward by economist Steven Levitt that the increased availability of legal abortion after the Supreme Court ruling in 1973 on Roe v Wade meant that fewer children were born to young, poor, single mothers.

BBC: US crime figures: Why the drop?