A former IRA prisoner is one of Sinn Fein's three nominees to the newly reconstituted Policing Board.
Martina Anderson will join the new Policing Board
Martina Anderson was convicted of conspiracy to cause explosions in England in 1986.
She is now an MLA for Foyle and the party's director of engagement with unionists.
She will join party policing spokesman Alex Maskey and North Antrim MLA Daithi McKay on the board, to be set up after the NI Assembly is restored on 8 May.
Ms Anderson said: "I will be going in to evaluate the performance of the PSNI and I will be going in there to hold them to account.
"I am a republican, I am a proud republican. Like many thousands of people out there I have been in prison, as have many thousands of others. At this moment in time it is important that we win the peace."
Mr Maskey said the party would play "a constructive role", providing a voice for communities.
"The Sinn Fein members on the Policing Board will provide the voice for communities who have in the past experienced only bad policing," he said.
"We want to play a constructive role on the board but we will not shy away from challenging, or criticising, or questioning policing decisions and policy when the need arises."
Last week, Sinn Fein held their first talks with the Northern Ireland Policing Board.
The party's leader, Gerry Adams, led a delegation to meet board chairman, Sir Desmond Rea.
Sinn Fein members voted to support policing in Northern Ireland for the first time in the party's history at the ard fheis, or conference, at the end of January.