The Supreme Court yesterday struck down as unconstitutional a law limiting campaign contributions in referendum fights.

Such limits have been imposed in a number of jurisdictions to combat the influence of well-financed special interests in voting over issues from rent control to tuition tax credits and nuclear power.

The court, striking down 8 to 1 a $250 limit imposed by Berkeley, Calif., said these contribution ceilings violate the First Amendment by imposing a "direct restraint on freedom of expression" and "political dialogue."

The ruling plainly jeopardizes a $2,500 limit in Maryland.

While it involved only ballot measures, not office-seekers, the ruling will undoubtedly be used to challenge federal campaign contribution limits because it further narrows the permissible zone of government regulation when it comes to elections. It treats campaign contributions with the same constitutional respect the court has previously given campaign expenditures, which have been shielded from restrictions on grounds they are a form of "free expression."

The complex federal campaign contribution ceilings are under attack from several quarters.

Landlords challenged Berkeley's law after the city enforced it to control contributions in a ballot dispute over rent control. Individual landlord groups had contributed as much as $5,000--20 times the $250 limit--in their unsuccessful effort in 1977 to defeat the proposition. Berkeley successfully defended the ceiling in California's Supreme Court as a tool to prevent domination of referenda campaigns by large contributors and argued that, in any event, it was only a minor infringement.

Chief Justice Warren E. Burger, writing for the court, disagreed yesterday. The limit "imposes a significant restraint on the freedom of expression of groups and those individuals who wish to express their views through committees," he wrote.

Ceilings on contributions to candidates for office have been upheld because they can corrupt office-holders, he said. But in a referendum there is no one to corrupt.

"Whatever may be the state interest or degree of that interest in regulating and limiting contributions to or expenditures of a candidate or a candidate's committees, there is no significant state or public interest in curtailing debate and discussion of a ballot measure," he said.

Referenda have been resorted to more and more frequently in recent years as voters have sought a direct voice in sensitive policy questions.

Five justices agreed with Burger's opinion in Citizens Against Rent Control et al. vs. City of Berkeley et al. Three--Justices Thurgood Marshall, Harry A. Blackmun and Sandra Day O'Connor--agreed with the result but gave their own reasons. Justice Byron R. White was the lone dissenter, saying the Berkeley ordinance "represents such a negligible intrusion on expression and association that the measure should be upheld."

In a second ruling yesterday, the justices said that poor defendants cannot sue their public defenders for monetary damages under federal civil rights law.

Russell Richard Dodson, an Iowa defendant, sued Martha Shepard, a Polk County, Iowa, public defender, alleging that she failed to represent him adequately in his appeal to the Iowa Supreme Court in a robbery case. He sought money damages from Shepard under Section 1983, the U.S. law permitting suits against public officials for violations of individual civil rights.

That law does not directly allow suits against private people. But in the past, the court has interpreted it broadly enough to allow actions against a private person acting with the authority of a state government, under "color" of law. Shepard and other public defenders are appointed and paid by government, Dodson argued, and could therefore be sued as if they are public officials.

Justice Lewis H. Powell, writing for the 8-to-1 majority yesterday, rejected Dodson's argument. A public defender representing a client is no different from a private lawyer representing a client, Powell wrote. The fact that the defender is appointed by the state does not change what is essentially a non-governmental private relationship, he said.

Powell noted that Dodson could still sue Shepard under state legal malpractice laws.

Blackmun dissented yesterday in Polk County vs. Dodson. He said the court was adopting a new and unacceptable test of what constitutes state action, a "functional" test dependent not on who employs the person being sued but on what the person happens to be doing at any particular time.

In another significant action yesterday, the court refused to review a New York ruling banning a form of "voluntary prayer" on public high school property when school was not in session. A Supreme Court ruling last week permitting prayers and Bible-readings on college campuses had raised questions whether the New York ruling and the Supreme Court's own 1962 decision banning religious worship in grade schools would stand.

Yesterday's action, taken without comment in Brandon vs. Board of Education of Guilderland Schools, is the Supreme Court's answer to those questions, for the time being.