Sandra Day O'Connor, after her first term as a Supreme Court justice, is a solid member of the court's conservative wing. In the session that ended July 2, Mrs. O'Connor voted to: v Give local school boards unlimit.ed power to remove books they find offensive from high school and junior high libraries. Her side lost. v Let Washington state voters bat a school busing plan voluntarily adopted by the city of Seattle to achieve racial balance. Again, she was on the losing end. v Allow states to execute "non-triggerman" ' criminals whose crimes resulted in a death even though they did not intend to take part in a killing. Another minority view. Mrs. O'Connor's overall voting record indicates just how much she has joined the court's conservative side since she was awom in last September. In the 31 cases decided by 6-4 votes - rulings that generally indicate the thorniest disputes between liberals and conservatives - Mrs. O'Connor sided with ultra-conservative justice William H. Rehnquist 27 times. She sided only four times in 5-4 decisions with Justice William J. Brennan, leader of the court's liberals. Only once were the three justices on the same side in a 6-4 ruling, a relatively minor case. In other key cases during the just-complet.ed term, the 52-year-old Mrs. O'Connor voted to: .,,,, Bar all lawsuits seeking monetary damages from U.S. presidents for misconduct in office. Her side prevailed. .,,,, Deny illegal alien children a free public school education. A; minority view. v