Washington, Apr 23 (AP) An appeals court resurrected the case today against four Blackwater Worldwide guards involved in a 2007 shooting in a Baghdad public square that killed 17 Iraqis.

A federal trial judge in Washington, Ricardo Urbina, threw out the case on New Year's Eve 2009 after he ruled that the US Justice Department mishandled evidence and violated the guards' constitutional rights.

A three-judge panel of the US Court of Appeals ruled Friday that Urbina wrongly interpreted the law. It ordered that he reconsider whether there was tainted evidence against four of the five defendants: former US Marines Evan Liberty, Donald Ball and Dustin Heard; and Army veteran Paul Slough.

The Justice Department has dismissed charges against a fifth defendant, Nick Slatten, a former US Army sergeant.

Blackwater security contractors were guarding US diplomats when the guards opened fire in Nisoor Square, a crowded Baghdad intersection, on Sept. 16, 2007.