Here are former Sen. Fred Thompson's positions on some key issues in the 2008 presidential race.

Abortion

In 1991, as part of his work in a law firm, Thompson consulted for an abortion rights organization. In June 2007 he said Roe v. Wade "usurped 200 years of law." He now says he favors returning abortion laws to the states. As a senator, he voted in favor of maintaining a ban on military base abortions, in favor of a ban on late-term abortions, and in favor of a ban on human cloning.

Climate

"Some people think that our planet is suffering from a fever. Now, scientists are telling us that Mars is experiencing its own planetary warming: Martian warming," Thompson wrote on April 13, 2007, on his ABCRadio.com blog. "It seems scientists have noticed recently that quite a few planets in our solar system seem to be heating up a bit, including Pluto. NASA says the Martian South Pole's ice cap has been shrinking for three summers in a row. Maybe Mars got its fever from earth. If so, I guess Jupiter's caught the same cold, because it's warming up too, like Pluto." As a senator, Thompson voted in favor of drilling in the Arctic National Wildlife Refuge, in favor of ending the Corporate Average Fuel Economy standards, or mandatory fleet mileage standards, and in favor of defunding renewable and solar energy research funding.

Guns

In speaking about the mass murder of 32 people at Virginia Tech, Thompson said, "The statistics are clear. Communities that recognize and grant Second Amendment rights to responsible adults have a significantly lower incidence of violent crime than those that do not. Incarcerated criminals tell criminologists that they consider local gun laws when they decide what sort of crime they will commit, and where they will do so. But Virginia Tech administrators overrode Virginia state law and threatened to expel or fire anybody who brings a weapon onto campus. Those 'Gun-free Zone' signs don't mean much to the sort of man who murdered 32 people."

Health

Thompson favors a free-market approach to health care. "Every American should be able to get health insurance coverage that is affordable, fully accessible, and portable. Coverage should meet their individual needs and put them in control," Thompson says. The syetem should promote cost-effective prevention, chronic-care management, and and emphasis on personal responsibility, embracing medical information technology. As a senator, Thompson voted against allowing reimportation of prescription drugs from Canada, against allowing patients to sue HMOs to collect punitive damages, in favor of limiting self-employment health deductions, and against increasing tobacco restrictions.

Immigration

When he was a senator, Thompson voted in favor of allowing more foreign workers into the United States for farm work, creating a national registry containing names of U.S. workers who want to perform temporary or seasonal agricultural work, and against restoring food stamp benefits to the children of illegal immigrants. On his ABCRadio.com blog he wrote, "I think it's time for a little plain talk to the leaders of Mexico. Something like: Hey guys, you're our friends and neighbors and we love you but it's time you had a little dose of reality ... A sovereign nation loses that status if it cannot secure its own borders and we are going to do whatever is necessary to do so."

Marriage

"I think that we ought to be a tolerant nation. I think we ought to be tolerant people. But we shouldn't set up special categories for anybody. And I'm for the rights of everybody, including gays, but not any special rights," he told Fox News on March 11, 2007. "You know, marriage is between a man and a woman, and I don't believe judges ought to come along and change that."

Taxes

"Taxes are necessary. But they don't make the country any better off. At best they simply move money from the private sector to the government. But taxes are also a burden on production, because they discourage people from investing and taking risks," Thompson said in a speech to Lincoln Club Annual Dinner in Orange County, Calif., on May 4.

Iraq

As a senator, Thompson voted in favor of using military force against Iraq in 2002. But, "We've got to rectify the mistakes that we've made. We went in there too light, wrong rules of engagement, wrong strategy, placed too much emphasis on just holding things in place while we built up the Iraqi army," he told Tennessee radio host Steve Gill. "I would do essentially what the president's doing (on Iraq). I know it's not popular right now, but we're the leader of the free world whether we like it or not. People are looking to us to test our resolve and see what we're willing to do in resolving the situation that we have there."