It was endorsed in referenda on both sides of the border in the hope that it would not only lead to peace and political stability but also bring justice for those who suffered at the hands of paramilitaries.
The jury is still out on political stability, with a fresh round of cross-party negotiations beginning today in a final attempt to save powersharing and devolved government.
It has undoubtedly succeeded in bringing an end to widespread violence.
Justice remains elusive.
Judging from the paltry prison sentence handed down this week to Gary Haggarty, one of the North’s bloodiest and most prolific murderers, the agreement has done little to ease the heartache of those bereaved.
The arrest on Tuesday in England of Freddie Scappaticci, the man named in 2003 as the British army’s notorious IRA agent codenamed Stakeknife, will test it further.
Stakeknife’s brutal exploits are widely known, but Haggarty is not a household name south of the border. On Monday the former UVF leader, after pleading guilty to five murders and 200 other terrorist offences, was sentenced to life in prison by Judge Adrian Colton, at Belfast Crown Court.
But his so-called life sentence for these brutal slayings was immediately reduced to six and a half years – all because he morphed from serial killer to police informer. Taking into account time spent on remand, he is likely to be a free man in a matter of months.
The peace process has seen many controversial and uncomfortable moments, among them the amnesty given in 2000 to dozens of paramilitaries. But it was never meant to facilitate anyone getting away with murder by becoming a supergrass for either the police or army in Northern Ireland.
The Good Friday Agreement is already under threat as a result of Brexit and the stalemate in efforts to return to a powersharing administration.
But the biggest threat it faces is British government disinterest and Irish government apathy.
Relatives of victims have announced plans for a mass march in Belfast later this month to demand action on stalled political efforts to deal with the legacy of the conflict.
Groups representing relatives of those killed have come together under the banner “Time for Truth” and urged people to join their protest on February 25.
Both governments must take their concerns seriously. The Good Friday Agreement was never meant to be an end in itself, but a means to an end — by definition, a process. That requires constant vigilance and engagement by both governments to ensure its success.
Otherwise, we risk creating a political vacuum that could — as in the past — be filled by those more willing to use the bomb and the bullet than the ballot.