JUST WHEN Montgomery County's exhaustive, years-long deliberations on a cable television franchise agreement seemed over, there is new static from five county council members. They have awarded the council a kind of new and unnecessary franchise: a whole set of broad regulatory powers, including--here's the most novel and superfluous part--an antitrust provision like no other in the country.

The immediate effect is to jeopardize the county's agreement with Tribune-United of Montgomery County, whose attorneys have said all along that such a provision could make the company subject to criminal prosecution by the state's attorney for alleged anticompetitive behavior, as defined by the council resolutions. The measure also requires the firm to submit on request a "competitive impact statement."

For example, according to one council member, if Tribune-United were to allocate one of its channels to a burglar alarm company offering home protection via cable, then the cable company would have to make the same offer to all burglar alarm companies, or be subject to criminal prosecution or civil suits. Perhaps it should have to make the same offer. But is unclear exactly what effect the county law would have beyond state or federal law.

Council president David L. Scull argued that the county needs its own antitrust law in case federal or state antitrust statutes do not apply--even though local governments everywhere else generally avoid getting into complex antitrust questions. Says council vice president Esther P. Gelman: "Whatever we've done to overprotect the public interest can only be to our credit."

And if it results in the collapse of a franchise agreement and a new and maybe even lengthier negotiation, Montgomery residents and taxpayers can credit that to the council majority as well. Member Rose Crenca, in opposition, had a good question: She wondered if the bill "is just a nuisance bill to punish the franchisee who won, or is there another contractor waiting in the wings?"