At Catholic University, the law professors are forming a union. In New York City, hundreds of lawyers already belong to unions and some have gone out on strike. Government lawyers, both in Washington and in regional offices, are unionized.

They are in the forefront of a growing movement of lawyers - especially those working for salaries in public defender, neighborhood legal services and legal aid programs, all aimed at the poor - who are joining unions both for the traditional aims of more money and better working conditions and to bring about what they consider a better deal for their clients.

"More and more staff attorneys - payroll people, they are really workers - are beginning to join unions," said Jules Bernstein, associate general counsel of the Laborers' International Union of North America.

"Because there is a tendency on the part of those who provide legal services for the poor to try to get the most out of limited resources," Bernstein said, "sometimes they forget the economic needs of the staff in favor of more services to poor clients. So unionization is a natural reaction on the part of employes and staff."

The growth of the union movement among lawyers is being fueled by the expansion of programs, many funded by the federal government, in which lawyers work on salaries.

It runs parallel to a similar trend toward unionization among salaried doctors such as interns and residents, who supply much of the medical care in hospitals, and those doctors employed by prepaid health care groups.

The doctors at Group Health Association, a Washington prepaid group, staged a strike last spring for a higher wages and better working conditions. Moreover, interns and residents across the country also have gone on strike - sometimes over the issue of better patient care, but often for bread and butter salary issues that have greatly increased their pay and reduced the hours they work.

"It's clearly true there are more unions now than there were five years ago. Whether they will continue to grow is something I don't know," said Thomas Ehrlich, president of the federally funded Legal Servies Corp., which has unions in 23 of its more than 300 neighborhood legal services programs.

James Braude, who resigned as head of New York City's 280-member Legal Services Staff Association to run the embryonic National Organization of Legal Service Workers, said another 20 unions are being formed in states as scattered as Maine, California and Arkansas.

As recently as last year, he said, there were fewer than a half dozen unions in the legal service network. His New York City union was formed in 1972 and is now the largest in the country. Its membership encompasses all legal service employes, including lawyers.

The 20-person full-time faculty of Catholic University's law school has formed a union, the Law Faculty Bargaining Committee, but the university is refusing to bargain with it. The case is now headed for the U.S. Court of Appeals here.

Harvey Zuckman, a law professor who is president of the Law Faculty Bargaining Committee, said faculty variety of reasons, including increasing their pay, which is lower than any other law school in the city.

"We've been working for years within the system and it just hasn't paid off," he said. "A number of us just got fed up."

It appears unlikely, however, that higher paid lawyers in private practice - where the starting salaries to new law school graduates have now reached $30,000 in the pace-setting New York firms - will join unions. Besides being well paid to start, young New York lawyers can look forward to becoming partners, whose salaries in the larges firms reach six figures.

A short walk from the Wall Street headquarters of many major New York firms are Manhattan's criminal courts, where lawyers for the Legal Aid Association represent a majority of the defendents.

These lawyers start at $13,500 a year - half the starting salary of their Wall Street colleagues - and peak after 13 years at $28,500.

The Association of Legal Aid Attorneya, founded in 1960, is "the forerunner of the unionizaiton trend," said its head, Craig Kaplan. The 600-member union, all lawyers, has already had two strikes; the first one, said a Columbia Law Review article in 1971 "was primarily directed toward needed reforms . . . and not toward wage increases alone."

Kaplan said the association was founded because of the poor working conditions of Legal Aid attorneys made it impossible to properly represent their clients. As a result of the strikes the union won a reduced case-load and a change in the way cases are assigned "so the individual Legal Aid lawyer can provide the kind of service one would expect from a private lawyer" said Kaplan.

Also in New York the largest existing prepaid legal plan in the country representing city employes belonging to the American Federation of State County and Municipal Workers set up a union in June. Fifty lawyers paralegals and social workers belong to the Municipal Employees Legal Services Staff Association and will be bargaining with their management - in this case another union.

There is some conflict between attorneys and other workers in unions. In California for instance attorneys of Rural Legal Assistance honored the picket line set up by the United Legal Workers during a 10-week strike that ended in June. But the lawyers handled cases from their homes because they felt it would be unethical to abandon their clients explained Mary Ann Massenberg, a legal secretary who is the union representative.

She called it "closet scabbing."

The American Bar Association at first took the position that lawyers could only join in a union with other attorneys, but a more recent opinion by the ABA's Committee on Professional Responsibility approved lawyers in mixed unions.