Competing theories of defenses to liability are being debated in advance of trial on the sole remaining wrongful death action charging negligence in the 9/11 hijacking of a commercial airliner.

Southern District Judge Alvin K. Hellerstein yesterday asked for briefs in Bavis v. United Airlines Corp., 02 civ 07154, a case brought by the family of Mark Bavis of West Newton, Mass., a professional hockey scout who was on United Airlines Flight 175 when it crashed into the World Trade Center’s South Tower on Sept. 11, 2001.