The Supreme Court yesterday ruled 5 to 3 that an employer can bar from a workplace a federal safety and health inspector who doesn't have a search warrant.

The decision is a moral victory for business and ideological groups who contended that the Constitution bars warrantless searches of commercial buildings as well as private homes.

"To hold otherwise would belie the origin" of the Fourth Amendment "and the American colonial experience," Justice Byron R. White wrote in the opinion for the court.

At the same time, however, the decision preserves the basic power of inspectors - with warrants - to make announced inspections under the Occupational Safety and Health Act (OSHA) of 1970.

In getting a warrant from an independent magistrate, moreover, an inspector, with or without prior notice to an employer, will not have to demonstrate probable cause in the criminal-law sense to believe that violations of OSHA exist.

"We are unconvinced . . . that requiring warrants to inspect will impose serious burdens on the inspection system or the courts, will prevent inspections necessary to enforce the statute, or will make them less effective," White said.

The "great majority of businessmen can be expected in normal course to consent to inspection without warrant," White said. The Labor Department, which administers OSHA, "has not brought to this court's attention any widespread pattern of refusal," he added.

White defused another major concern that had been expressed in advance of the ruling: the provisions for warrantless searches in laws governing a wide array of federal and state agencies would be invalidated along with the provisions in OSHA.

"The reasonableness of a warrantless search, however, will depend upon the specific enforcement needs and privacy guarantees of each statute," White said. And, he noted, some laws "already envision resort to federal court enforcement when entry is refused . . ." In this regard, he cited the Mine Safety Act and "exemplary language" in laws providing for Agriculture Department inspections of meat, eggs and other products.

The court acted in a case in which the central figure was Ferrol G. (Bill) Barlow, operator of an electrical and plumbing installation business in Pocatello, Idaho, a Democratic precinct committeeman and a leader of the John Birch Society.

At 11 a.m. on Sept. 13, 1975, a Labor Department compliance officer walked into Barlow's shop - unannounced and without a warrant - to check for possible OSHA violations. The law authorized routine inspections such as this "during regular working hours and at other reasonable times, and within reasonable limits and in a reasonable manner."

Barlow blocked the inspector, citing a "higher law," the Constitution, that keeps private property "secure . . . against unreasonable searches . . . " He pointed to a copy of the Fourth Amendment hanging over trays of Birch literature.

The inspector then went to a federal judge, who issued an order to Barlow to admit the inspector. But Barlow again barred him and, in the resulting litigation, prevailed when a three-judge panel ruled that the inspector should have sought a search warrant.

The government appealed to the Supreme Court. Its decision brought a wave of reactions.

At the Labor Department, Assistant Secretary Eula Bingham said in a prepared statement that "workers need have no fear that their safety and health will go unprotected," even though "the decision may ultimately require us to alter our inspection procedures somewhat."

Noting that the decision allows an inspector to choose a workplace for inspection on the basis of a "general administrative plan for the enforcement of the act derived from neutral sources," she said the ruling "thus falls right into line with our policy announced last year of directing 95 percent of our inspection activity toward high-hazard industries."

In response to reporters' questions, she and a top department lawyer said that "to the maximum extend possible" the department will seek warrants in advance. In cases where inspectors without warrants are turned away, they will seek a warrant immediately and return immediately.

The National Association of Manufacturers found "good news" in the warrant requirement and "bad news" in the determination that inspectors needn't show probable cause.

The National Federation of Independent Business Inc. foresaw a "dramatic" beneficial impact for small businesses.

The AFL-CIO said the decision may "delay and complicate" OSHA enforcement. The Chamber of Commerce of the United States applauded the court's "blow for freedom." The Associated General Contractors of America Inc. "saluted the court."

The American Conservative Union, which gave large sums to Barlow's legal treasury, hailed "a great victory."

In the dissenting opinion, Stevens wrote that routine OSHA warrantless searches are constitutionally reasonable, that the warrant procedure the majority approved "is essentially a formality," and that the court shouldn't "require formalities which merely place an additional strain on already overtaxed federal facilities."