The Supreme Court said yesterday that it will decide whether insurance companies can be sued under federal law for refusing to deal with policyholders.

The court will review a ruling by the First U.S. Circuit Court of Appeals that carved out an exception to regulation of insurance by the states, as decreed by a 32-year-old federal law.

The action was a victory for St. Paul Fire & Marine Insurance Co., three other large insurance firms, and three trade associations whose members write a significant portion of all property and casualty policies.

The core issue is a provision of the McCarran-Ferguson Act, with Congress enacted in 1945 to nullify a Supreme Court decision in the previous year that insurance was interstate "commerce" subject to federal regulation.

Although McCarran-Ferguson allowed the states generally to pre-empt relevant federal laws, it contained a provision that the Sheriman antitrust act remains applicable "to any agreement to boycott, coerce, or intimidate, or any act of boycott, coercison, or intimidation."

The First Circuit decision arose from a complaint by Rhode Island physicians that the boycott exception entitled them to seek treble damages from St. Paul Aetna. Hartford and Travelers for drastically shrinking their insurance coverage for malpractice.

In line with several other decisions a federal judge ruled against the doctors. Overturning him, the First Circuit said. "To exclude consumers of insurance from the basic protection afforded by the boycott provision . . . cuts against a basic policy of antitrust law." Mutual Fund Disclosure

The court refused to review a ruling that will have a widespread disruptive impact on the mutual fund industry, according to F. Eberstadt & Co. and the Investment Company Institute. But according to Chemical Fund, Inc., and Susan Tannenbaum, the beneficiaries of the ruling, it will have no widespread impact at all.

The ruling, handed down in March by the Second U.S. Circuit of Appeals, said that Eberstadt, as manager of Chemical Fund, was required by Securities and Exchange Commission rules to disclose in proxy statements for the years 1967 through 1972 that it had considered and rejected re-capture of "excess" brokerage commissions. Unauthorized Patent Law Practice

Unauthorized Patent Law Practice District of Columbia Court of Appeals barring Washington chemical engineer H. Lawrence Blasius from engaging in the practice of law. This was defined in the case of Blasius and his Washington Patent Office Search Bureau as advertising offers to conduct patentability searches and to advise on patent matters.