The city school board went to Superior Court yesterday, in an effort to force the D.C. government to restore $7.2 million it has cut from the current school budget.

The board filed motions for a temporary restraining order and a preliminary injunction, based on a 1976 case filed by the school board that prevented then-mayor Walter Washington from freezing $2.7 million in unspent salaries.

The latest legal challenge was spurred by a new procurement policy for all city agencies that had been implemented last spring. The policy, which may affect the school system's proposed $350 million fiscal year 1985 budget as well as this year's budget, was designed to prevent city agencies, including the school system, from carrying fiscal obligations over from one fiscal year to the next. The city's public schools stood to lose $7.2 million for goods ordered in fiscal 1982 that were delivered in fiscal 1983.

After the school board voted to go to court over the policy change, Mayor Marion Barry put off the new purchasing policy until next year. But Barry decided to take $7.2 million back from the schools anyway by invoking a city charter provision that allows him to apportion potential deficits among all city agencies.

School officials said yesterday that the city already has taken $4.7 million and the motions seek to get that money back. The motions also seek to see that goods ordered by the school system are paid for with funds from the fiscal year in which they are ordered, regardless of when they arrive.

The school system's success or failure in the case will affect both its purchasing policy and the size of future budgets. The school system would have to order goods earlier than usual to ensure that they are delivered in the same fiscal year.

The loss of $7.2 million from the current budget would mean that goods the school system wanted this year would have to come out of fiscal 1984 funds, which already are fixed at $326 million and awaiting congressional approval. It may then affect the amount the school system requests in fiscal 1985.

School Superintendent Floretta D. McKenzie has begun a long budget process by proposing a fiscal 1985 schools budget of $350,361,000 that calls for no new programs and represents a 7.4 percent increase over the fiscal 1984 budget.

The fiscal 1985 budget would not take effect until Oct. 1, 1984, but the budget process continued last night when the board conducted the first of two public hearings.

A House-Senate conference is scheduled today on the fiscal 1984 budget. The D.C. school system may get an additional $1.5 million in fiscal 1984 for a study on merit pay for teachers.

School officials said that much of the $24.3 million increase that the superintendent wants in fiscal 1985 comes in the form of $15 million in estimated pay raises for school system employes.

The other $9.3 million includes $2.5 million to upgrade school facilities, and another $3.8 million for anticipated increases in prekindergarten enrollment. Other parts of the increase are geared toward special education students and to replace 45 buses for handicapped students.