Politics is to blame for the decline of unions in the U.S., according to a new report by the Center For Economic And Policy Research, a progressive think tank. Of the world's 21 richest countries, those with more of a free market philosophy witnessed the greatest drop in union influence over the last 30 years.

Wealthy European nations, as well as Japan, Australia, New Zealand, Canada, the U.K., Ireland and the U.S., have near identical levels of globalization and technology, says the report, therefore those two factors can't explain the precipitous decline of American unions. Over half of the workers in several of these countries are unionized, after all, compared to just 12 percent in the U.S.

The researchers found that social democratic countries (Scandinavia), which have the highest levels of government regulation, have seen the tiniest drop in union sway. In fact, union coverage (the percentage of employees covered by wage bargaining agreements) increased by 5 percent between 1980 and 2007, the most recent year for which data is available. Union membership declined by just 5 percent.

Continental market economies like Germany and France, which have lower levels of regulation, experienced greater declines than Scandinavia: 4 percent for coverage, and 14 percent for membership.

Unions in liberal market economies like the U.S., Japan and the U.K., which dance more faithfully to the tune of the market, saw more substantial erosion: 26 percent for coverage and 23 percent for membership.

Mapped out this way, it's perhaps not surprising that in 2007 the U.S. had the lowest union coverage rate (13.3 percent), followed by Japan and New Zealand (16.1 and 17 percent). Scandinavian countries all had rates of 74 percent or more, and two-thirds of the countries were above 50 percent.

The researchers set out to attack the idea that technology or globalization are responsible for the dramatic decline in unionization. Of course, it's always possible that these forces had an impact which was simply offset by the greater labor protections in certain countries.

But this is also something of a straw man; the fact that deregulation and anti-union sentiment has weakened organized labor over the last half century has long been argued in the U.S.

After the Depression, the country actively sought to reduce competition, argues Michael Wachter, director of the Institute for Law and Economics at the University of Pennsylvania Law School, in a 2007 research paper. Companies were allowed to act in concert to set wages higher than free market levels, as long as they shared that bounty with their employees. A third of workers joined unions. It was the golden age of organized labor.

"Labor unions are woven into our economic pattern of American life, and collective bargaining is part of the democratic process," declared Eric Johnston, a U.S. Chamber of Commerce president in the 1940s. "I say recognize this fact not only with our lips but with our hearts."

But the nation's relationship with unions soured in the 1980s. Companies became more willing to hire strikebreakers, and in 1981 President Reagan famously fired 11,000 illegally striking air traffic controllers.

When Gov. Scott Walker banned collective bargaining rights for Wisconsin's public workers earlier this year, he crystallized a debate that has been simmering for decades. On the one side are those who see unions as defenders of the middle class and a counterweight to the concentrated power of corporations. On the other side are those who see them as obstacles to competitiveness and unfair concentrations of power themselves.

There is evidence to support both sides. A study published in August showed that the decline in union power was responsible for a third of the increase in income inequality among men since 1973, and a fifth of the increased inequality among women.

But an analysis in 2000 by two Princeton researchers asserted that the central reason for the decline of organized labor in the 1970s and '80s was that nonunionized companies grew while unionized companies shrank. In small part, this was because unionized industries were fading more generally, but mostly it was because nonunionized firms, with higher labor costs, just couldn't compete as well.

When unions were a greater part of our national fabric, they lifted the wages of all Americans. Now that such a small minority of workers are unionized, the opposite has occurred. Some private sector workers have fallen furiously into the anti-union camp. Frustrated that their unionized counterparts in the public sector get a better deal, they push for cuts to government workers' benefits and rights.

Some call it justice. Others call it a race to the bottom.