SHOULD teenagers be required to have a parent's consent before ending a pregnancy?The question is among the most contentious in the evolving debate over abortion. Forty-one states now have parental-consent or parental-notice laws. But half are not being enforced because of court challenges. Now both sides are awaiting a verdict in a California case that will be a bellwether in the legal maneuvering over the issue. The dispute centers on constitutionality of a 1987 state law requiring unmarried minors to get consent from a parent or judge before having an abortion. Testimony in the month-long trial in San Francisco concluded last week, with the last of some 30 witnesses. The decision now rests with Superior Court Judge Maxine Chesney, who is expected to rule within a few months. Buoyed by United States Supreme Court rulings upholding parental-consent laws, abortion foes hope the nation's most populous state will do the same. More than 400,000 teenage abortions are performed in the US each year, 10 percent in California. "It is a very important case," says Ralph Johnson, a California deputy attorney general and one of the lawyers defending the law. Abortion-rights advocates believe a victory here would set a precedent in allowing state constitutions to be invoked to overturn parental consent laws. The case is a key test of California's privacy guarantee. Like a number of other states, California offers stronger and more explicit protection for the right to privacy and abortion than the federal government. Some believe the important battles in the future will be fought outside Washington. "Given the bad signals coming from the US Supreme Court, one of the important forums for protecting reproductive rights will be the states," says Margaret Crosby of the American Civil Liberties Union, one of the lawyers challenging the statute. Opposing the law is a coalition of doctors, youth advocates, and civil libertarians. Defending it are the state's attorney general and county district attorneys. In presenting some two dozen witnesses - including psychologists, judges, and counselors - opponents argued that the state's privacy provision applies equally to adolescents and adults. Witnesses testified that requiring consent can trigger a family crisis. It risks forcing girls into motherhood before they are ready, or into an illegal abortion, because teens are afraid to talk to parents. Seeking the OK of judges, they argued, is a time-consuming, intimidating process. Lawyers for the state called psychology, health, and family experts in maintaining that abortion is too big a decision for minors to make alone. They see the law as a justifiable attempt to protect adolescents and preserve the parent-child relationship. Both sides presented conflicting views of a teen's ability to make mature decisions and how consent laws have worked in other states. No matter what the court rules, the decision will be appealed.