TEN HOURS after it began, a marathon meeting of the Montgomery County Planning Board came to a close last week having settled one question: Did the developer and builders of Clarksburg Town Center violate height regulations with their 50-foot-tall residences? By a 5 to 0 vote, the board offered a resounding yes.

But it didn't come easily. Some planning documents supported the citizens group that first called attention to the infractions; others backed the landowners' contention that they were bound only by a commitment to make each townhouse and condominium building four stories, regardless of height. After much deliberation, board members concluded that the developer and the builders constructed more than 400 townhouses and one 30-unit building that shattered height limits set forth in at least one binding document.

Such a transgression should not go unpunished, especially when the products of the breach tower over a quaint historic district like Clarksburg. (The board's decision spares current homeowners; houses that have been built or are under contract will not have to be altered.) Board members shrewdly postponed the decision on an appropriate monetary penalty until they could investigate area residents' concerns that this was part of a larger pattern of altering the site plans. The defendants argue that they should not be fined, and, to be fair, many of the planning documents were vague about height restrictions. But neither ignorance nor lack of enforcement is a credible excuse for flouting the rules.

That said, the hundreds of flagrant violations in this one community do indicate a rather spectacular failure of enforcement. The two departments that pointed fingers at each other over who exactly was responsible for measuring the buildings in Clarksburg -- the Planning Board and the Department of Permitting Services -- have been directed by the County Council to conduct a review of all subdivisions approved since 2002 to determine whether they conformed to their approved plans. The council compounded the accountability problem by announcing that the investigation of what went wrong will be conducted by the Office of Legislative Oversight -- yet another county agency. The council is unwisely contradicting planning officials' earlier promise of an independent review, which would identify problems and recommend procedural improvements without creating a situation in which the players are refereeing their own game.

Meanwhile in Clarksburg, what's done is done. A substantial penalty, together with a comprehensive reform of the county's inspection process, will ensure that developers who disregard regulations do so at their peril.