America was riveted -- and riven -- this week by the execution of one of its least defensible mass murderers, Timothy McVeigh, the man responsible for the deaths of 168 people in the bombing of the Alfred P. Murrah Federal Building in Oklohoma City six years ago. At the same time, Japan was traumatized by a mass murder of its own: the fatal stabbing of eight elementary-school children in Osaka last Friday.

The two crimes were obviously quite different in nature, but each bore in its own way on the debate about capital punishment that has internally divided both societies for years, particularly as other developed countries have moved on to a seemingly irreversible rejection of judicial killings no matter what the crime or provocation.

McVeigh -- like the Aum Shinrikyo cult members who killed 12 people in a sarin-gas attack on the Tokyo subway in 1995 -- serves as a kind of ultimate test case on the issue. The self-confessed and by all accounts unrepentant killer is to the capital-punishment debate what Adolf Hitler is to the just-war debate. If anyone is going to justify the argument for a state's right to execute its most violently antisocial members, McVeigh is the man. Describing the children who died in the Murrah Building's day-care center as "collateral damage," he never retreated from his view of the crime as a "legit tactic" against a government he deemed a threat to individual liberty. Conversely, if even McVeigh is to be exempt, then the objections to capital punishment are clearly absolute.