The protests over the president's decision to authorize military tribunals to try terrorists call to mind Barry Goldwater's remark that "extremism in defense of liberty is no vice."
Stripping away the name-calling about kangaroo courts and star chambers, most of the arguments seem to be that there is only one way to conduct a trial, no matter what the offense and despite the fact that the Supreme Court in the past has not found these special tribunals to be inconsistent with the Constitution.
This inflexible approach is, in a way, as extreme as the views that condone terrorism itself, and the consequences of adopting it would ultimately help terrorism achieve its purposes. A little thought will reveal the problem the president confronts. Bringing Osama bin Laden and his henchmen to justice in a US court could require the government to reveal sensitive intelligence information, which could make it difficult to stop other terrorists. Yet without the information gained through intelligence sources, it could be impossible to convince a jury that these criminals and terrorists are guilty beyond a reasonable doubt.
Even in revealing secret intelligence, it may not be possible to meet the standards of a US criminal court for convicting Mr. bin Laden or his co-conspirators. When the criminal justice system deals with organized crime, it is frequently unable to gain convictions without the testimony of someone who has direct knowledge of the culpability of the Mafia boss.
That's why the traditional method of reaching the top of a crime organization is to convict those lower down and work up the chain with testimony of those already convicted or in jeopardy of conviction. These witnesses can provide evidence that a person ordered a crime, even though he did not actually perform the criminal act. This doesn't always work; witnesses may not be willing to talk or there may be none. Al Capone was famously convicted only of tax evasion, when he probably ordered many murders.
The inability to convict a criminal does not mean he is innocent. We have set the standards for conviction very high, because, in balancing society's risks against the risk of punishing an innocent person, we would rather let the guilty go free than convict the innocent. That is a policy with which few in a civilized society will quarrel, but we should recognize it as striking a balance between two competing objectives.