American Bar Association President David R. Brink warned today that legislation before Congress to strip the federal courts of jurisdiction over controversial social issues could "lead to the most serious constitutional crisis" since the Civil War.

He called on attorneys, because of their "special responsibility as guardians of the rule of law" to declare battle against these proposals, which he said were "almost unbelievably" making unexpected headway in Congress.

Brink made his remarks in a speech to the National Conference of Bar Presidents, meeting here along with the American Bar Association.

Conservatives have introduced at least 32 proposals in Congress to remove federal court authority in such controversies as abortion, school busing and school prayer in retaliation for Supreme Court rulings they consider objectionable. Such bills generally would leave these matters to the state courts, where conservatives say they think they will have better luck.

Brink's statement was unusually strong for the head of an organization that prides itself on moderation on political issues. The ABA is run largely by lawyers with large commercial law firms. But the growth in power of conservatives, often on the strength of issues involving the law and the courts, has placed the ABA increasingly in the role of protester.

The organization has waged a massive effort against President Reagan's efforts to eliminate federally financed legal services.

Brink said the fight against the court-stripping bills would be the second "great fight" of this period. "We must join as partners and companions in arms," he said.

These proposals, Brink said, "threaten elimination of the third branch of federal government, the judicial branch." He said they also threaten "the Constitution as the supreme law of this land. And if we lose that, we lose our system of government."

Giving each state court system exclusive jurisdiction over the issues, he said, would "convert America into a kind of league of independent states instead of one nation."

Brink asked each state and local bar association to follow the lead of the ABA and adopt resolutions against such legislation. He also asked that lawyers engage in "a massive letter-writing campaign and personal visits to members of Congress."

The bars, he said, should also fight similar proposals now circulating in state legislatures to take jurisdiction away from state courts over these matters.