The Supreme Court ruled yesterday that a suburban community can bar housing projects for low and moderate-income if it has no proved intention to discriminate racially, even though its population is nearly 100 per cent white.

Only if racial discrimination is proved to be "a motivating factor" does a bar to such housing deny the equal protection of the laws guaranteed by the Constructions, the court held.

The court said that the Chicago suburb of Ailington Heights had not been shown to have violated the 14th Amendment when it refused to rezone a 15-acre tract to permit construction of a 19unit housing project.

The court reversed a decision by the Seventh U. S. Circuit Court of Appeals that the zoning action was unconstitutionally discriminatory because of its "ultimate effect" on blacks, even though the action had been motivated by the concern of Arlington plans.

In initial reactions, lawyers seeking to open the suburbs to federally financed, integrated public housing said the reversal does not seriously set back their cause, and possibly does not set it back at all.

One reason, they said, is that in the opinion for the Supreme Court, Justice Lewis F. Powell Jr. laid down standards by which an intent to discriminate against minorities - such as departure from normal administrative procedures - can be demonstrated.

Another reason was cited by Martin E. Sloane general counsel of the non-profit National Committee Against Discriminatuin In Housing.

Sloane pointed out that the court sent the case back to the appellate court for further consideration of claims that the refusal to rezone violated the Fair Housing Act of 1968, which may be found to make proof of racial discriminmation less difficult than the 14th Amendment. The court did not address this point.

Customarily, courts try to decide whether a law has been violated before reaching the question of constitutionality. For unexplained reasons, the appellate court did not decide whether the housing law had been violated. Instead, it proceeded in what Powell termed " a somewhat unorthodox fashion."

Joining with Powell were Chief Justice Warren E. Burger and Justices Potter Stewart, Harry A. Blackmun and William H. Rehnwquist. Justice John Paul Stevens, who came to the high court from the Seventh Circuit, took no part in the case.

The court spilt 5 to 3 on how to dispose of the case, although two of the dissenters, Justices Thurgood Marshall and William J. Brennan Jr. had concurred in the majority analysis.

Justices Byron R. White agreed with the majority that the case should be sent back for consideration of the statutory issue.But he dissented, as did Marshall and Brennan, to the refusal of the majority to permit the appellate court to reconsider its ruling in the light of a sunsewuent Supreme Court decision.

In that decision, written by White and handed down last June 7, the court said that blacks challenging an entrance test for policemen in the District of Columbia - or challenging any law or government action - must, prove a "racially discriminatory purpose" to show a constitutional violation.

White's dissent in the Arlington Heights case protested that the majority "given no reason for its failure to follow our usual practice" of letting a lower court have the benefit of the June decision.

White alone objected to the court's "lengthy discussion" of the standards sfor proving 14th Amendments violations, such as legislative or administrative history that "may be highly relevant."

Arlington Heights as of the 1970 census had 27 black residents in a population of 64,000. It also had, from the time it adopted its first zoning ordinance in 1959, a single-family classification for a site owned by a religious order called Clerics of St. Viator.

In 1970, the order and the Metropolitan Housing Development Corp., a nonprofit developer formed to build low-and moderate-income housing, reached an agreement under which MHDC would build 30 two-story apartment buildings on the 15-acre parcel - provided the Village Plan Commission would rezone it.

After public meetings at which both advocates and opponents addressed the issue of introducing public housing that probably would br racially integrated, the commission and then the Village Board denied rezoning.

In June, 1972, the MHDC and three blacks sued the village. They lost in U. S. District Court, which held that the denial of rezoning had been based on a desire "to protect property values" and the integrity of the zoning plan.

While approving the ending about the integrity of the plan, the Seventh Circuit observed that the refusal to rezone would have a disproportionate impact on blacks, who constituted 40 per cent of the Chicago-area residents eligible to become residents of the proposed project.