One of the finest features of the British legal system to be adopted in the United States is trial by jury. And one of the most valued rights protected in this country, but not specifically in Britain, is freedom of information. This week, both were the subject of debate in England, where a jury acquitted a British civil servant who had been prosecuted for violating the Official Secrets Act. The case could not have been brought here, and it is likely that the decision of the British jury will spur reconsideration of the wisdom of such prosecutions there.

The case arose when Clive Ponting, a senior civil servant at the Defense Ministry, learned in the course of his work that a Cabinet member had given inaccurate information to Parliament, and had refused to correct it, in order to conceal the events surrounding the sinking of an Argentine ship, the General Belgrano, during the 1982 Falklands war. Mr. Ponting sent two government documents to an opposition Labor Party member of Parliament that showed the original information to be deceptive.

Specifically, the documents showed that the Belgrano, rather than sailing toward the British task force as the government had said, actually had been sailing away from it for 11 hours, and that the ship had been spotted a day earlier than the official explanation had stated. The torpedoing of the cruiser took 368 Argentine lives and, arguably, removed what prospects of negotiation remained at that time.

Mr. Ponting was indicted under the 1911 Official Secrets Act, a sweeping measure that makes it a crime for a government worker to discuss or pass information of any kind to any unauthorized person, even if the information has nothing to do with national security. The statute is broad enough to be used against whistle-blowers disclosing procurement frauds and against government employees such as Mr. Ponting who reveal information that is politically damaging to the party in power.

While this country has no Official Secrets Act, it makes much use of the stamps that classify documents and keep them in locked files. Gen. William Westmoreland's current suit against CBS, for instance, is providing Americans with much new information about the internal disputes in the command of an American war that ended a dozen years ago. The British jury's verdict is a victory for the principle that the legal protection of military secrets should not outlive the military emergency that justified the secrecy. It is a principle that might usefully be applied more widely in this country, as well as Britain.