The amendments would narrow the reach of the War Crimes Act, which now states in general terms that Americans can be prosecuted in federal criminal courts for violations of "Common Article 3" of the Geneva Conventions, which the United States ratified in 1949.
The risk of possible prosecution of officials, CIA officers and former service personnel over alleged rough treatment of prisoners arises because the Bush administration, from January 2002 until June, maintained that the Geneva Conventions' protections did not apply to prisoners captured in Afghanistan.
The Supreme Court decided in Hamdan v. Rumsfeld on June 29, however, that the administration's policy of not honoring the Geneva Conventions was illegal, and that prisoners in the fight against al-Qaeda are entitled to such protections.
http://www.washingtonpost.com/wp-dyn/content/article/2006/08/08/AR2006080801276_pf.html