Former Senator Fred D. Thompson of Tennessee, who has not officially declared his presidential ambitions, took a not-very-veiled swipe yesterday at the leading Republican candidate, former Mayor Rudolph W. Giuliani of New York, for supporting gun control. Mr. Thompson, who starred in “Law & Order,” wrote on his Web site: “When I was working in television, I spent quite a bit of time in New York City. There are lots of things about the place I like, but New York gun laws don’t fall in that category.” Then he decried a recent court ruling on a gun case, writing that...