On January 1, 1967, the California Evidence Code began to govern trials held in California courts. Because of the delays necessarily incident to litigation, the appellate courts were not called upon to review trials held under the new rules in significant numbers until 1968. With the 1968 decisions, however, the impact of the Code upon California practice has become fairly apparent. At the same time, the courts have continued to develop rules of evidence designed to implement the various procedural guarantees found in the Constitution of the United States, and some of these court-developed rules have had significant effect, particularly in criminal cases. Meanwhile, the legislature was content to make few, and only minor, changes in the statutory law of evidence. Thus the principal arena for securing changes in evidence law has shifted from the legislature to the courts.