Busy day!

The Supreme Court begins an unprecedented three days of arguments in what could turn out to be one of the biggest cases of our lifetimes. The high court will take up the President's health care overhaul. Attorney's from 26 states who are opposed to the new laws will face off against Justice Department lawyers. It pits the President against many GOP Governors. It also could end up being a major part of the 2012 elections. A decision from the Court could come as early as this summer. We're covering the story from every angle today.

On the campaign trail, Rick Santorum handily won the Louisiana primary on Saturday. Next up Wisconsin, Maryland and Washington DC next Tuesday. Rick Santorum getting into it a little with a New York Times reporter..

...CANDIDATES

NEWT GINGRICH / DE

1900EDT -- Delivers remarks to the New Castle, Sussex & Kent County GOP Member Meeting at the Fire House, 1225 Old Lancaster Pike, Hockessin, DE. FNC LIVE via LiveU

RON PAUL / TX

No events planned

MITT ROMNEY / CA

1240EDT -- Holds rally at NuVasive, Inc, 7475 Lusk Boulevard, San Diego, CA. FNC LIVE via LiveU

RICK SANTORUM / VA

No events planned

President Obama is in Seoul, South Korea attending a nuke summit. The President is urging North Korea to "pursue peace" and change its ways. The North Koreans are planning to test a missile next month. South Korea threatening to shoot it down.

James Cameron - the Director of "Titanic" - has returned to the surface after diving to the Earth's deepest point, The Mariana Trench, in a specially designed sub.