WASHINGTON (Reuters) - U.S. business groups on Tuesday renewed their campaign to amend an anti-foreign bribery law, suggesting authorities should give companies additional defenses against criminal charges. The U.S. Chamber of Commerce and others have complained the Foreign Corrupt Practices Act, a 1970s-era law that bars U.S. companies and others from paying bribes to officials of foreign governments in exchange for business, is ambiguous. So far they have unsuccessfully lobbied Congress to amend it. ...