A strict alcohol policy implemented at all public universities in Massachusetts after the deaths of two college students in 1997 is effective but has been enforced inconsistently, according to a study by two Harvard researchers.

“There was a fairly strong correlation between lower drinking rates and stricter enforcement of the policy,” said John R. Knight, co-author of the study which will be published in the October issue of the Journal of Studies on Alcohol.

The new restrictions were enacted after two students—Scott Krueger of MIT and Adam Prentice of the University of Massachusetts at Amherst—died of alcohol-related causes within two days of each other in Sept. 1997.

“[The Massachusetts Board of Higher Education], which has jurisdiction over all public colleges and universities, voted to crack down on drinking,” said Knight, who directs the Center for Adolescent Substance Abuse Research at Children’s Hospital of Boston and is an assistant professor of pediatrics at Harvard Medical School.

The policy restricts alcohol on public campuses to specific locations, requires advanced registration of all social gatherings involving alcohol and creates new sanctions for violations, including parental notification and expulsion, Knight said.

The study, which took place between 1998 and 1999, measured drinking rates among students, as well as the perceptions of administrators, security officials and students about the policy’s enforcement, according to a press release.

Knight said drinking rates at the 11 colleges surveyed in the study varied between 36 and 71 percent. These figures point to a decrease in heavy drinking rates at schools where the policy was strictly enforced, according to Knight.

But perceptions about the enforcement of the 1997 restrictions varied.

At one college only 35 percent of students said that the new policy was strictly enforced, while at another 90 percent said that it was. College names were not mentioned in the study.

Dean of the College Benedict H. Gross ’71 has said that curbing underage and irresponsible drinking at Harvard will be one of his priorities as dean.

He told The Crimson in May that he hoped to offer more social opportunities and spaces for students so that they would be less likely to resort to alcohol in their leisure time.

Knight said that there was no single solution to the prevalence of alcohol on college campuses.

“There isn’t a simple solution. I’m a medical doctor. I’m against death and all the health problems associated with alcohol,” he said. “You need a multi-faceted approach to combat this problem. Strict enforcement, however, might be needed to control the heaviest drinkers.”

Henry Wechsler, the director of the Harvard School of Public Health College Alcohol Studies Program, also collaborated on the study.

Wechsler declined to comment for this story.