PRODDED BY teachers unions, Maryland lawmakers decided this year to penalize any local school system that would reduce per-pupil spending, no matter how generous its education funding. The effect is to render past funding increases irreversible — and to wave a large red flag at local officials who might consider going beyond state-mandated increases in the future.

The burden of the new state law falls heaviest on Montgomery County. Spending there on schools, particularly on teachers’ salaries, is the highest in the state and much higher than in other suburban school systems in the Washington area. Now, regardless of future economic conditions, it is locked into extremely high funding levels, as a new report by Montgomery’s Office of Legislative Oversight explains. Because of rising student enrollments, the county will be required to give its schools an additional $23 million in local funding next year.

Joshua Starr, the Montgomery schools superintendent, has chosen not to use those funds for fresh classroom initiatives or for cutting class sizes or even rehiring hundreds of laid-off career counselors and specialized teachers. Instead, he opted this spring to grant pay increases for existing teachers — a two-year raise that will average nearly 7 percent for most teachers. That will consume nearly almost all of the increased funds.

That decision was unwise. In effect, Mr. Starr, who oversees the system’s $2 billion budget, has elected to cut staffing levels, even as enrollment continues to climb, in order to boost pay for remaining teachers. The question isn’t whether teachers deserve higher salaries; they do. The question is whether Montgomery can afford to plump up teachers’ salaries way beyond levels at comparable school systems, and at the cost of funding other priorities.

A useful point of comparison is Fairfax County, which has similarly high-ranked schools. The pay increase in Fairfax is unlikely to exceed 3 or 4 percent over two years. Overall, salaries for teachers in Montgomery will be about 20 percent higher than in Fairfax.

To address other priorities, Mr. Starr would have to increase his budget by more than the state-mandated minimum. Doing so would amount to a gauntlet thrown down before the Montgomery County Council, which allocates school funding. This year, Mr. Starr ignored the council’s request to hold school salary increases in check. If he asks for a large budget increase for next year when he submits his spending plan in December, in effect he will be demanding that the council either slash spending on police, firefighters, parks and other county agencies, or raise already high local taxes.

The council would be foolish to accede to such demands. Any budget increase beyond state-mandated per-pupil levels would be irreversible under Maryland law. If Mr. Starr cannot live within those funding constraints, he isn’t worth his salt as a manager.