HISPANICS and other minorities who have been seeking greater clout in the political arena are increasingly turning their attention to another white-dominated institution, the courts.In a move with potentially far-reaching implications, Latinos in Monterey County in northern California have filed a federal lawsuit aimed at changing the ethnic makeup of a local court. The move, the first of its kind in California, seeks to secure greater minority representation by challenging the system of electing local judges. A similar lawsuit was recently filed in New Mexico by native Americans. Both actions invoke the federal Voting Rights Act to try to change the face of the judiciary. While similar lawsuits have been brought in the past, mainly by blacks in the South, the statute has been used primarily by minorities seeking greater access to legislative and executive positions. In June, the US Supreme Court ruled that the Voting Rights Act could be used to challenge judicial elections. Thus legal experts and advocacy groups expect the law to become an increasingly popular tool to try to put more blacks, Hispanics, and others in judicial robes. "People are moving and will move in the future to institute more lawsuits," says Robert McDuff, an attorney with the Lawyers Committee for Civil Rights Under Law in Washington, D.C. No current comprehensive statistics exist on the makeup of the American judiciary. A 1985 study by the Fund for Modern Courts in New York found that, of 12,000 full-time, law-trained judges in state courts nationwide, 12.6 percent were women and minorities. Blacks represented 3.8 percent of the total, Hispanics 1.2 percent. While experts believe the numbers have changed significantly in some areas since then, minority-advocacy groups argue that the judiciary remains a closed institution. At least 16 lawsuits have been filed across the country using the Voting Rights Act to try to put more minorities on the bench. Most of the suits are still in the courts. Some of these challenge the selection of judges statewide, others for a single district. Forty states select at least some of their judges by popular vote. "I think we will see more suits filed," says Anthony Champagne, a professor of government and politics at the University of Texas at Dallas, who follows these cases. "But the legal outcome of all this is still unclear." The suit brought against Monterey County, an agricultural area south of San Francisco, seeks to change the way Municipal Court judges in the area are selected. The suit contends that the current system of voting for judges in one consolidated, at-large district is illegal and dilutes Latino voter strength. Hispanics want the county divided into separate districts that would give minority judges a greater chance of being elected. Joaquin Avila, the attorney who filed the suit on behalf of five local activists, says no more than one Hispanic has ever reached the bench in Monterey County, even though the population is 40 percent Latino. Mr. Avila was involved in a similar suit that forced the county to move from at-large elections to single-member districts for the Watsonville City Council. Members of the County Board of Supervisors seem sympathetic to the activists' concerns, and a political compromise is likely. If Avila and his allies are successful in inducing change - either through the courts or Board action - it will likely spur similar moves up and down a state whose demographics are changing rapidly. "It could be very, very important," says Cruz Reynoso, a former state Supreme Court justice who is now a law professor at the University of California at Los Angeles. "The judiciary in California is not very diverse."