Reading The Riot Act

It all looked sadly familiar. After a parade by Northern Ireland's Orange Order was diverted from a Catholic area, members and supporters of the Protestant brotherhood rioted. Over most of last week, cars were burned, blockades were erected and gunmen turned automatic weapons on police. Most people thought spectacles like this were a thing of the past.

The unionists' chief enemy, the I.R.A., announced in July that it was giving up its armed campaign and would dispose of all its weapons. Unionists claim the violence broke out because concessions to the I.R.A. had shown that violence pays. "I...