Congress passed a bill last year adding lighters to the list of
items prohibited in the cabin. The ban started mid April 2005.
Lighters haven't been permitted in checked bags for at least 30
years because they might start fires in cargo holds. The reason for
the ban was the failed shoe bomber, Richard Reid, who tried
unsuccessfully to light explosives hidden in his shoes on a
trans-Atlantic flight in 2001. He used matches.