"Yet most empirical studies of the relationship between unionization and important safety outcomes, such as injuries and fatalities, have failed to find any statistically significant evidence of a 'union safety effect,'" the report said.

And in fact, the results of the research Morantz did are also somewhat mixed.

The report outlines a "very sizeable, robust and statistically significant" increase in non-traumatic injuries, defined as those caused not by a specific incident, but by cumulative or repetitive problems.

The results for total injuries are similar, but are more muted, the report says. Unionization is related to 25 percent fewer total injuries compared to non-union mines in the mid-1990s, but that disparity decreases in later years, the report says.

Morantz attributes those numbers in large part to more accurate and complete reporting of injuries at unionized mines.

The report found that traumatic injuries, those involving specific incidents, showed a "highly significant" decline at union mines compared to non-union operations. The difference is even larger -- at least 45 percent -- if fatalities alone are examined, the report said.

"There have been tragedies at mines where the UMWA represents the workers, most recently nearly 10 years ago at the Jim Walters No. 5 Mine in Brookwood, Ala.," Roberts said. "We in the UMWA learned hard lessons in that tragedy and others that preceded it. We took steps to provide a better protection for our members, and this study demonstrates that those steps are working. We will continue to work as hard as we can to keep the miners where UMWA members work the safest in the world."

Reach Ken Ward Jr. at kw...@wvgazette.com or 304-348-1702.

Read the study online.

CHARLESTON, W.Va. -- Union coal mines are significantly safer than non-union mining operations, according to a new report from a Stanford University law professor.

Alison D. Morantz found a "substantial and significant decline in traumatic mining injuries and fatalities" at underground mines where workers were members of the United Mine Workers union. The disparities were especially pronounced among larger mines, Morantz found.

The report, published last week by the John M. Olin Program in Law and Economics at Stanford, found that, over the last two decades, there have been between 18 and 33 percent fewer traumatic injuries at union mines, compared to non-union operations. It found 27 to 68 percent fewer fatal accidents at union mines over the same period. The range in figures accounts for possible statistical variations because of a small sample size.

"This is a groundbreaking study that quantifies the profound differences in safety underground coal miners experience when working union versus working non-union," said UMW President Cecil Roberts. "The simple truth is that union mines are safer, and this study proves that."

In her report, though, Morantz explains that most of the studies on the matter show it's not exactly that simple.

"Empirical literature on the relationship between unionization and workplace safety presents a curious puzzle," she wrote.

"On the one hand, scholars have documented numerous ways in which unions help to promote safe work practices," she wrote. "For example, unions typically play a critical role in educating workers about on-the-job hazards, incentivizing workers to take greater care on the job, attracting more safety-conscious workers, inducing employers to mitigate known hazards, increasing regulatory scrutiny, and developing safety-related innovations.

"Yet most empirical studies of the relationship between unionization and important safety outcomes, such as injuries and fatalities, have failed to find any statistically significant evidence of a 'union safety effect,'" the report said.

And in fact, the results of the research Morantz did are also somewhat mixed.

The report outlines a "very sizeable, robust and statistically significant" increase in non-traumatic injuries, defined as those caused not by a specific incident, but by cumulative or repetitive problems.

The results for total injuries are similar, but are more muted, the report says. Unionization is related to 25 percent fewer total injuries compared to non-union mines in the mid-1990s, but that disparity decreases in later years, the report says.

Morantz attributes those numbers in large part to more accurate and complete reporting of injuries at unionized mines.

The report found that traumatic injuries, those involving specific incidents, showed a "highly significant" decline at union mines compared to non-union operations. The difference is even larger -- at least 45 percent -- if fatalities alone are examined, the report said.

"There have been tragedies at mines where the UMWA represents the workers, most recently nearly 10 years ago at the Jim Walters No. 5 Mine in Brookwood, Ala.," Roberts said. "We in the UMWA learned hard lessons in that tragedy and others that preceded it. We took steps to provide a better protection for our members, and this study demonstrates that those steps are working. We will continue to work as hard as we can to keep the miners where UMWA members work the safest in the world."

Reach Ken Ward Jr. at kw...@wvgazette.com or 304-348-1702.