The battle for the Republican nomination has moved to Florida this week, which also happens to be a key battleground in an entirely different fight: the $15bn federally-waged war on drugs.

Passed in July of last year, a controversial law requires the state's welfare recipients to submit to drug testing – and to pay for the costs of the screening. Nearly 1,600 applicants refused to submit to the testing last year, while over 7,000 took the test and passed. Thirty-two of the applicants failed, the majority of whom tested positive for marijuana.

The law was temporarily blocked in October, but required testing for federal aid has become a hot-button issue in drug policy debates, and has received the explicit endorsement of Newt Gingrich. The American Civil Liberties Union filed a lawsuit on behalf of a 35-year-old single father who objected to the legislation, arguing the law violated his 4th amendment rights

With more than 100,000 inmates, the Sunshine State's prison system is the third largest in the country, and costs $2.1bn a year to maintain, according to Julie Ebenstein, policy and advocacy counsel with Florida's chapter of the ACLU.

Ebenstein believes that inmates serving time for drug charges would be better – and more affordably – served by treatment rather than spending time behind bars.

In addition to devastating countless families, Ebenstein argues the drug war in Florida has amounted to a massive misappropriation of taxpayer dollars – an injustice that often resonates among conservative voters.

"The tough on crime policies have neither abated crime nor abated drug use," Ebenstein argues. They have instead, "burdened the state with these huge increasing costs of prisons."

The issue of drug policy has not come up much in the debates so far, but each of the four remaining Republican candidates – Gingrich, Mitt Romney, Rick Santorum and Ron Paul – has addressed it in some form in the past. A primer on where they stand:

Newt Gingrich

Newt Gingrich / Reuters

As House Speaker, Gingrich introduced the Drug Importer Death Penalty Act of 1996, which would have legalized the execution of any person caught smuggling drugs into the US more than once, so long as the individual carried 100 or more doses (an ounce of high-grade marijuana could conceivably qualify). First time offenders would have faced life in prison and defendants would have a window of just 18 months to file their one and only appeal.

While the law did not pass, Gingrich expressed his support for, in his own words, "very draconian" measures as recently as last year. In an interview with Yahoo News last November, Gingrich noted how "successful" Singapore has been in its response to drug trafficking.

"They've communicated with great intention that they intend to stop drugs from coming into their countries," Gingrich explained.

Brad Adams, executive director of Human Rights Watch Asia Division, has a different take. "Singapore routinely executes people for drug trafficking. They consider themselves as having about the harshest drug laws in the world," he said. "It's not something to be emulated."

Following in Singapore's footsteps, he pointed out, would require the US to send, "thousands and thousands of people to death sentences annually."

In addition to importing authoritarian models of criminal justice, Gingrich is an outspoken advocate of making it "expensive to be a drug user" by requiring federal aid applicants to submit to drug tests.

Of last year's major drug war initiatives, drug testing is "the principle issue," said Ethan Nadlemann, the executive director of Drug Policy Action, an organization that works across party lines to advocate for alternatives to the drug war.

"It's a remarkably invasive and ugly policy," he argued, adding that, "There's lots of evidence that it's ineffective and costly."

Nadlemann called Gingrich "basically a nightmare" when it comes to issues of drug policy.

"For a guy who's supposed to be an intellectual and intelligent, the quality of the argumentation on his part is embarrassing".

Mitt Romney

Mitt RomneyAFP/Getty Images

While Mitt Romney has been less vocal in his views on drug policy, his record as governor of Massachusetts and his interaction with potential voters suggests a deep reluctance to reform.

In one 2007 video a medical marijuana user asks if the former Massachusetts governor would have him arrested for his choice of medication. After saying that he is opposed to medical marijuana, Romney turns his back on the wheelchair-bound young man, leaving his question unanswered.

"Even apart from the medical marijuana," Nadlemann says, "he has been just terrible on this issue."

Nadlemann refers back to 2006, when then-governor Romney vetoed a bill allowing pharmacies to provide individuals clean hypodermic needles without a prescription. The measure would have cost the state nothing, and health experts argued it would help curb the spread of infectious disease. In addition, proponents noted, it would have saved funds otherwise spent on emergency medical care.

Romney argued the program would have "unintended consequences" and encourage the use of heroin. The Massachusetts legislature ultimately overturned Romney's veto, joining 47 other states that allow access to clean needles.

Rick Santorum

Rick Santorum/Getty Images

Like Romney, Rick Santorum has been relatively quiet on the issue of drug policy. Also like Romney, a videotaped encounter has provided insight into what the former Pennsylvania senator knows – or chooses to ignore – about drug policy.

Earlier this month Santorum was confronted by a member of the group Students for Sensible Drug Policy. The candidate, who has framed himself as a champion of family values, was asked whether he would continue to send non-violent drug offenders to prison as president, a punishment that routinely tears families apart.

Santorum responded, "Wow … the federal government doesn't do that."

In fact, drug offenders make up nearly half of the federal prison population, almost 100,000 people. According to the US department of justice, in 2009 the most serious crime committed by over 95,000 prisoners was a drug charge.

In a second video posted by the group this year, Santorum cops to being uninformed. When asked about states' rights and the federal government's role in enforcing medical marijuana laws, the presidential hopeful says, "I don't know my medical marijuana laws very well." He then goes on to say, "they are a hazardous thing for society."

Ron Paul

Ron Paul/Getty Images

An ardent libertarian, Ron Paul stands apart from his competitors. Paul has explicitly called for an end to the war on drugs, arguing the effort amounts to a colossal waste of money. He did not mince words speaking during a November presidential debate when he said flatly, "I think the federal war on drugs is a total failure."

Paul points to the disproportionate impact drug laws have had on communities of color resulting in the ballooning prison population. Running for president in 1988, he made a stop at the National Organization for the Reform of Marijuana Laws. It was the same period in which a series of racist newsletters bearing his name were being circulated. Still, the congressman from Texas noted discrepancies in the persecution of ethnic groups based on the substances they were believed to enjoy.

Paul pointed out that while ethnic groups were persecuted for their association with certain substances, the abuse of alcohol, which he argued was the preferred intoxicant of congressmen, was not used as pretext for targeting people.

More recently Paul has said that the prohibition of drugs in the United States directly contributes to Mexico's soaring death toll – now estimated at least 50,000 – by bankrolling ultra-violent cartels.

Like alcoholism, Paul claims, drug abuse should be treated as a medical issue. He has co-sponsored legislation in favor of medical marijuana and believes that Drug Enforcement Agency raids on medical marijuana clinics are unconstitutional.

At its core, Paul believes the drug war represents an unjustifiable assault on individual liberty.

"Ron Paul has been excellent," Nadlemann remarks.

Nadlemann describes Paul's presence in the ongoing race as "refreshing" and says comments regarding the drug war have been spot-on. "They're strong, they're smart and it's encouraging the way they're getting substantial applause in the primary debates."