Dave Thearle, a member of the United Mine Workers of America, waves an American Flag during a labor rally in Waynesburg, Pa., Friday, April 1, 2011. (AP Photo/Keith Srakocic)

There’s a new study out from a Stanford Law School professor that addresses an issue that comes up quite often here on Coal Tattoo: Whether union coal mines are safer than non-union operations.

The conclusion? Here’s what professor Alison D. Morantz concludes:

Although the United Mine Workers of America (UMWA) has always advocated strongly for miners’ safety, prior empirical literature contains no evidence that unionization reduced mine injuries or fatalities during the 1970s and ‘80s. This study uses a more comprehensive dataset and updated methodology to examine the relationship between unionization and underground, bituminous coal mine safety from 1993 to 2008.

I find that unionization predicts a substantial and significant decline in traumatic mining injuries and fatalities, the two measures that I argue are the least prone to reporting bias. These disparities are especially pronounced among larger mines.

My best estimates imply that overall, unionization predicts an 18-33% drop in traumatic injuries and a 27-68% drop in fatalities. However, unionization is also associated with higher total and non-traumatic injuries, suggesting that injury reporting practices differ substantially between union and nonunion mines. Unionization’s attenuating effect on the predicted frequency of traumatic injuries seems to have grown since the mid 1990s.

You can read the whole study by visiting this link and clicking where it says “One Click Download.” The paper is called “Coal Mine Safety: Do Unions Make a Difference?” Morantz, by the way, is a former union-side labor lawyer, and this paper was produced as part of the John M. Olin Program in Law and Economics at Stanford.