For the first time since Prohibition, possession of alcohol by students under the age of 21 is a punish-able offense, thanks to a change in Massachusetts state law.

An amendment made last spring to state law, which formerly prohibited only the purchase and serving of alcohol to minors, now additionally prohibits possession.

Tutors or proctors who discover students violating the policy will issue an informal warning, according to a letter issued today to registering first years and later this week to upperclass students. Second offenders will be sent a letter from a senior tutor or proctor which will remain in the student's file.

Underage students caught possessing alcohol more than twice will be punished by the Administrative Board and possibly be required to undergo mandatory alcohol treatment, according to the letter.

"This is new territory," said Associate Dean of Housing Thomas A. Dingman `67, a member of the Ad Board. "The punishment could range from an admonition to probation."

University administrators and senior tutors promised they would take the new law seriously and enforce it.

"The College certainly expects proctors and tutors will uphold this new policy," said Assistant Dean for Co-education Virginia L. McKay-Smith '78.

And federal inspectors threaten to make sure the University keeps its word. "If we failed to comply or failed to endorse the effort, we would lose federal funding, including financial aid money," Dingman said.

In the same letter issued at registration, the College "strongly encourages events and entertainment without alcohol."

Still, many officials said they are grudginglycomplying with the new law. "This is unfortunate,"said Dean of the College L. Fred Jewett '57yesterday. "We wish the University was not in aposition to police this."

Senior tutors interviewed yesterday alsoexpressed disappointment with the new policy.

"This makes it very difficult for us," saidGarth O. McCavana, senior tutor at Kirkland House."I'm going to suggest that students get in touchwith their state senators or representatives."

Some suggested that it will create moreantagonism between tutors and students.

"The tutors won't be able to look the other wayas much," said Julian P. Chang, senior tutor ofCabot House. "They could go to a bar with astudent before, but now it will be different."

Tutors said party life may go down a bit.

"I think that people in rooming groups where noone is over 21 will be reluctant to have bigparties now," said Greg Mobley, senior tutor ofWinthrop House.