LONDON — BRITAIN'S houses of Lords and Commons are confronting each other over whether to put on trial people suspected of committing ``crimes against humanity'' in World War II. The rare clash between the elected lower house of Parliament and the unelected ``peers of the realm'' is presenting the Thatcher government with what has the makings of a major constitutional crisis.
Prime Minister Margaret Thatcher also must soon decide whether Parliament is legally and morally justified in attempting to prosecute naturalized British citizens for crimes allegedly committed nearly half a century ago under Adolf Hitler's rule during World War II.
The two houses of Parliament found themselves at loggerheads when the Lords voted 207 to 74 against a war-crimes bill that had passed the Commons in March by a margin of 273 to 60.
Normally the upper house, consisting of a mixture of hereditary aristocrats and appointed ``life'' peers whose titles lapse when they die, supports the government in its voting patterns. But on June 4, after long and passionate debate, the Lords decided that Mrs. Thatcher should think again about the legislation.
The prime minister must either reintroduce the bill and invite another rebuff from the Lords or abandon moves to prosecute the suspected war criminals.
Parliament decided to take up the issue following publication of an official report recommending the prosecution of three individuals said to have committed war crimes and urging further investigation of more than 100 other cases.
The report said the proposed legislation was justified.
Many of the suspects are people of advanced years (some are in their 80s). All are East Europeans or from the Baltic states. They arrived in Britain after World War II, claiming to be Soviet refugees. They are accused of supporting the Nazi war effort and carrying out Hitler's policy of punishing subject peoples.
When the war-crimes bill went before the Commons last March, Thatcher gave members of Parliament (MPs) a free vote. The bill proposes to allow the British legal authorities to prosecute people whose alleged crimes occurred in another country. Existing British law does not permit this. The debate revealed deep divisions of opinion within Thatcher's Cabinet.
David Waddington, the home secretary, is solidly in favor of changing the law to enable prosecutions to go ahead.
Sir Geoffrey Howe, the deputy prime minister, is just as adamantly opposed. So is Douglas Hurd, the foreign secretary.
One of the most persuasive voices on the Commons benches was that of Sir Bernard Braine, a leading Conservative MP and ``father of the house'' (its oldest member). He continues to maintain that it is ``morally right'' to change the law.
Ivor Stanbrook, another leading Conservative backbencher, disagrees: ``It would be a tragic mistake to institute war-crimes trials and stir up emotions of hatred and revenge. I cannot see how those prosecuted could receive a fair trial.''
In the Lords, the similar arguments were heard, but much ``heavy artillery,'' in the shape of distinguished peers, appeared for the debate, and the debate went heavily against the bill.
Lord Shawcross, a prosecutor at the Nuremberg war-crime trials, said passing the bill would impose ``an indelible blot on every principle of law and justice.''
Lord Hailsham, who served for seven years as Thatcher's lord chancellor (the highest law officer), said: ``Justice cannot be done by this bill. I will vote my conscience.''
Robert Runcie, the archbishop of Canterbury, who was abroad when the vote was taken, sent a message back to London saying he was opposed to the measure.
This brought him into conflict with Lord Jakobovits, the chief rabbi of England. He said that defeat for the bill would make it certain that there would be no justice for millions of victims.
``It has been said that the bill is 40 years too late, but 40 years of moral negligence is no cause for persisting in it after it has been brought to light,'' he said.
The size of the Lords majority at first stunned Thatcher and Mr. Waddington who, at a Cabinet meeting two days later, counseled the prime minister to ``let the dust settle'' before deciding whether to reintroduce the bill in the Commons.
A week later, sources at 10 Downing Street indicated that Thatcher was determined to place the bill before the lower house again. But this drew a rebuke from Lord Whitelaw, Thatcher's former deputy, who urged her in a public statement on June 17: ``For goodness sake, don't do any more about it.''
A high proportion of Thatcher's parliamentary constituency are Jewish. She has been warned by supporters of the original bill that if she decides to drop it, a Conservative MP will reintroduce the measure as a private member's bill.
If the Lords were to vote against it a second time the government would have the right to ignore its verdict, but this would be certain to whip up a major controversy as to whether the House of Lords should be abolished.