Washington ? The Irish Republican Army has flashed a spotlight at an ideal moment on its own deeply ingrained criminality. The hard men of Northern Ireland have ensured that St. Patrick’s Day 2005 cannot be confined to green beer, leprechauns, ethnic pride or political expediency.

March 17 is no longer just a day for the Irish and their friends to march, drink and swap folk tales. It has become a benchmark for assessing the diplomacy and the politics of a decade-old effort to transform a violent revolt born in social injustice into national reconciliation.

The significant event of the day is one that will not happen: Gerry Adams will not be welcomed in the Bush White House. As with Yasser Arafat, shunning will become a tool for depriving the Sinn Fein leader of the credibility, favorable media attention and fund-raising opportunities he received in previous years as peace efforts flourished.

Even Sen. Edward Kennedy, D-Mass., who has often turned a blind eye to bad Irish behavior and promoted fund-raising that benefited the IRA, has had to gag on the events of recent weeks as IRA members mounted a $50 million bank robbery, slaughtered 33-year-old forklift driver Robert McCartney after a Belfast barroom brawl and terrorized potential witnesses, and then cavalierly offered to execute two of its own members for the crime when McCartney’s sisters courageously and vociferously demanded justice. (The sisters declined the “offer.”)

Kennedy joins President Bush in snubbing Sinn Fein, which is the political arm of the IRA and a participant in the Northern Ireland peace process launched by Bill Clinton, British Prime Minster Tony Blair and the government of Ireland.

The savage spree by IRA members — and the organization’s open “contempt for the rule of law,” in the words of a Kennedy spokesman — should not be portrayed as a failure of the Northern Ireland process. In important ways, this eruption of lawlessness underlines the importance of such talks — when they are managed with clear-eyed realism and a willingness to call a killer a killer.

As in daily journalism, timing is everything in the peace-process business.

Violent “revolutionary” movements attract criminals and psychopaths as well as idealistic justice-seekers and sincere nationalists. The longer the revolt continues the more likely it will become a criminal enterprise essentially devoted to self-perpetuation. That clearly has happened to the IRA, as it did to the Palestinian movement under Arafat.

Put to the test at Camp David in 2000, Arafat went on auto pilot to insurrection. The Northern Ireland process has at a minimum served a similar purpose: It has helped establish and clarify the fault lines between the IRA’s criminal bosses and those in the organization who would accept the rule of law and a new political order based on compromise.

Adams has posed as spokesman for the latter group for the past decade, without having to prove it. He must now do so or be treated as part of the problem. The Sinn Fein leadership has been given enough in the peace process to take control of a movement for which a peaceful, legal outcome is in fact an option.

How that works is being demonstrated by Mahmoud Abbas as he struggles as Arafat’s successor to get control over terrorism, corruption and open criminality in the Palestinian Authority. He appears to have convinced Bush and Israel’s Ariel Sharon that he is making an honest effort that deserves carefully balanced support. They are right in that judgment — for now.

Without Clinton’s attempt at Camp David — and the former president’s open denunciations of Arafat for thwarting peace efforts there — Bush would have had more difficulty in isolating the Palestinian leader and then, more importantly, moving quickly to offer support to Abbas once he moved to create change.

The cold shower Adams received when he arrived in Washington this week is similarly all the more important because of the contrast it provides to the times when the IRA seemed tempted by peace. As the term “peace process” implies, such efforts exist on a continuum of events that are neither totally independent nor totally predictable. Criticizing Clinton for extending his embrace too soon and too warmly to Adams or Arafat, or Bush for withholding his, misses that point.

Fate has given Bush a chance to push the peace process forward in the Middle East, and cause to pull it back in Northern Ireland. Leadership is about making distinctions in hard cases. Even politicians from heavily Irish communities have been doing that this St. Patrick’s Day. They must not relapse once the spotlight leaves them or the IRA.

— Jim Hoagland is a columnist for Washington Post Writers Group.