Traditionally a hated symbol of British occupation in the eyes of republicans, the Royal Ulster Constabulary was subjected to root-and-branch reform in the late 1990s under the recommendations of the Independent Commission on Policing in Northern Ireland. Lord Patten, fresh from governorship in Hong Kong, headed the commission and in 1998 drafted reforms aimed at winning over Sinn Fein. The RUC was replaced with the Police Service of Northern Ireland, symbols of Britishness were removed from uniforms and measures taken to encourage Catholics to join the predominantly Protestant force.

But many republicans remain to be convinced. At least five of Sinn Fein's assembly members plan to boycott next month's elections and several with close Irish Republican Army links have threatened to stand as old school republican independents against Sinn Fein candidates.

Undaunted, Mr Adams told the conference: 'The decision we've taken is truly historic. We have taken the opportunity to change the political landscape on this island and advance our cause of a united Ireland through building greater political strength.'

Critics like historian and author Ruth Dudley Edwards see darker motives in Mr Adams' drive for greater republican involvement in policing. 'It is difficult for terrorists, criminals and subversives to get their way when pesky policemen try to subject them to the rule of law,' Dudley Edwards says. '[Controlling] the police is exactly what Adams has been intent on throughout his long and grim career, through the use of intimidation, propaganda and political blackmail.'

Variously described as a traitor by diehard republicans, a terrorist by pro-British unionists and a visionary by those seeking an end to 30 years of violence, the enigmatic Mr Adams has taken Sinn Fein in a direction that the party's founding fathers would never have imagined, much less countenanced. During the course of the peace process that ended the so-called Troubles which cost 3,500 lives, he has put pragmatism above party principle in pursuit of a settlement.

An accomplished campaigner and negotiator, Mr Adams secured the Sinn Fein leadership in 1983 and won a seat in the British parliament for his West Belfast constituency. He nominally retains the seat but, due to his refusal to swear allegiance to Queen Elizabeth, does not participate in the Westminster system.

By 1986 he had overturned the party's long-standing policy of refusing to sit in the Irish parliament; more than a decade later he persuaded his fellow republicans to take the even bigger step of occupying seats at Stormont in a short-lived legislature borne out of the 1998 Good Friday Agreement.

He brokered IRA ceasefires in 1994 and 1997 that had limited success but paved the way for the Good Friday accords that are the basis of the relative peace enjoyed by Northern Ireland. And despite the IRA's pledge that 'not a bullet and not an ounce of explosive' would be surrendered to appease Britain and the unionists, in 2001 Mr Adams prodded the paramilitaries into decommissioning their weapons.

For some observers, it was his finest hour. But critics argue the issue is an example of Mr Adams' shrewd brinkmanship. The dangled promise of putting the IRA's arsenal beyond use was the Sinn Fein leader's trump card at the negotiating table for four more years until independent verification of disarmament was confirmed in 2005.

Convincing the IRA to lay down its arms furthered the peace process but provided ammunition to those who see a direct connection between the Sinn Fein leader and one of the world's most formidable terrorist organisations. Sinn Fein is widely regarded as the political wing of the IRA, but the party insists the two bodies are separate. Mr Adams has denied ever being a member of the IRA but over the years the British security services, the Irish authorities and the media have cited a large body of evidence to the contrary.

Speaking in 2005, Irish Foreign Minister Dermot Ahern said: 'We're absolutely satisfied that the leadership of Sinn Fein and the IRA are interlinked. They're two sides of the one coin.' His comments came after Irish Justice Minister Michael McDowell publicly accused Mr Adams and Sinn Fein's chief negotiator, Martin McGuinness, of being members of the IRA's ruling army council.

The British government was sufficiently convinced of Mr Adams' involvement in terrorism in the late 1980s to impose a media ban on him. In a move described by then-prime minister Margaret Thatcher as 'denying terrorists the oxygen of publicity', British television viewers were for seven years allowed to see pictures of Mr Adams but prohibited from hearing his voice, which was dubbed over by an actor.

Born in West Belfast, a Catholic working class area, Mr Adams was the oldest of 10 children raised by diehard republican parents. His father, Gerry Adams Snr, was an IRA foot soldier who served an eight-year jail sentence after he was shot and wounded in a botched raid on a Royal Ulster Constabulary patrol in 1942.

The son became a barman after leaving school but was soon drawn into the civil rights movement that gripped Belfast in the late 1960s as poor Catholics took to the streets to air grievances over religious discrimination.

For his part in the growing unrest, Mr Adams was interned without trial by the British. His influence in republican circles was soon recognised, however, when in 1972, aged just 24, he was released to accompany an IRA delegation invited to London to negotiate what turned out to be a brief truce.

From there he climbed quickly through the Sinn Fein ranks, becoming the target of several assassination attempts at the hands of his protestant loyalist enemies. His wife and son survived a bomb attack on the family's Belfast home and Mr Adams was badly wounded in 1984 when a death squad from an outlawed loyalist group, the Ulster Freedom Fighters, sprayed his car with automatic rifle fire.

While the sectarian bloodletting that blighted Northern Ireland until the turn of the century is still fresh in the minds of many in the province, Mr Adams has famously declared 'the war is over'. However, the battle for a meaningful democracy remains. Sinn Fein can argue it has delivered on its part of the bargain with decommissioning and police recognition - but it remains to be seen whether unionists will co-exist in Stormont with a party that retains its ultimate dream of a united Ireland free of British rule.