For many years, those who consider themselves to be libertarians have been fairly reliable members of the Republican coalition. Although no libertarian would consider himself or herself to be entirely in agreement with either major party, they have historically sided with the GOP. But the relationship today seems more deeply strained than any time in the last 30 years, and a divorce may be forthcoming. Basically, libertarians are allied with the right on economic issues and the left on everything else. They believe in the free market and freedom of choice in areas such as drugs, and favor a noninterventionist...