If union density is declining in the United States (and it is), it’s because unions can’t compete in the global economy, right? That’s the story we’re often told, anyway, but a new Center for Economic and Policy Research report says that actually, politics plays a major role (PDF). The CEPR study compares 21 countries with rich economies and facing similar levels of globalization and technological progress, and finds different outcomes for unions depending on the countries’ differing political environments.

The study looks at both union membership and union coverage, which is the number of people who are covered by collective bargaining agreements regardless of whether they are union members. (In the United States, the two numbers are fairly close; in many countries, though, significantly more workers are covered by collective bargaining agreements than belong to unions.) The result is that:

Countries strongly identified during the postwar period with social democratic parties—Sweden, Denmark, Norway, and Finland—have generally seen small increases in union coverage and only small decreases in union membership since 1980.

Over the same period, countries typically described as “liberal market economies”—the United States, the United Kingdom, Australia, New Zealand, Ireland, Canada, and Japan—have generally seen sharp drops in union coverage and membership.

Countries in the broad Christian democratic tradition, sometimes referred to as “coordinated market economies” or “continental market economies”—Germany, Austria, Italy, the Netherlands, Belgium, France, and Switzerland—typically have had outcomes somewhere in between the social democratic and liberal market economies, with small drops in union coverage and moderate declines in union membership.

That declining union membership and coverage in the U.S. is in part a result of political forces shouldn’t come as a surprise to anyone who has watched Wisconsin Gov. Scott Walker and Ohio Gov. John Kasich’s assaults on public employees or read about Sen. Lindsey Graham’s threats to the National Labor Relations Board before it filed a complaint against Boeing. But since anti-union politicians and corporations always tell you that their assaults on workers’ rights are because unions can’t work in an era of globalization, this study offers a simple rejoinder.

This blog originally appeared in Daily Kos Labor on November 22, 2011. Reprinted with permission.

About the Author: Laura Clawson is labor editor at Daily Kos. She has a PhD in sociology from Princeton University and has taught at Dartmouth College. From 2008 to 2011, she was senior writer at Working America, the community affiliate of the AFL-CIO.