Never mind the rush to rent tuxedos and pick out the perfect dress — local high-schoolers now have yet another thing to worry about before attending prom: passing the new breathalyzer test.

The nearby towns of Milford and Trumbull are among 12 state school districts — out of a total 166 across Connecticut — that have begun administering breathalyzer tests to all high-school students before social gatherings such as dances or sporting events. Area school officials have defended the tests as an effective way to reduce underage drinking, but some, such as the local executive director of the American Civil Liberties Union, have questioned their constitutionality by asserting that the tests violate the students’ rights to privacy.

Several New Haven Public Schools officials did not return calls Tuesday inquiring about whether the city plans to implement similar tests. A spokesman for the state Department of Education said implementing breathalyzer tests is a local prerogative that should be decided by individual school boards.

Earlier this month, the Milford Public Schools district introduced the tests as a preemptive step to combat the increasing frequency of teenage drinking, Milford Superintendent Harvey Polansky said.

“[The occurence of alcohol-related incidents] is a national epidemic,” he wrote in an e-mail. “We did not recommend the policy due to a specific event.”

Polansky said that seeing the same program being used successfully in the nearby Trumbull Public Schools district, which implemented the tests about two years before Milford, showed that the tests have favorably deterred the amount of underage drinking in high school.

But not everyone in the community is convinced of the wisdom of the new regime. In last Sunday’s New Haven Register, ACLU of Connecticut Chief Executive Officer Andrew Schneider said the ACLU is asking school districts to stop testing students without suspicion, which the ACLU believes violates the Fourth Amendment prohibition against “unreasonable” searches and seizures.

Schneider could not be reached for comment Tuesday.

Trumbull High School Principal Robert Tremaglio, however, had a different take.

“Not testing everyone could be said [to be] a bias and prejudice against those vulnerable to danger,” Tremaglio said, “and this would be against constitutional rights.”

Thomas Murphy, public-information officer of the stae Department of Education, said implementation of breathalyzer tests is a local policy that can only be regulated by a specific district’s administrators and school boards.

“The Department of Education thinks it is permissible to institute this device,” he said, “but the state department does not regulate or provide any direction.”

Responding to the ACLU’s recent objections to the program, Murphy said the legal grounds for testing students before extracurricular activities and before normal school days are entirely separate, and schools are not violating constitutional rights by using the tests only for after-school events.

“Participating in an extracurricular is a privilege,” he said. “It is not part of the school program or the school day, so to speak, so the students have an option of attending. So if they opt to attend and understand in advance that they may be subject to drug testing, then the fact that they’re participating in the activity indicates their acceptance of those rules.”