Human rights groups in Haiti are demanding the United Nations be held more accountable after a Canadian police officer who was suspected of sexually assaulting a Haitian woman then left the country.

The man was one of more than 80 Canadian police officers serving with the UN Stabilisation Mission in Haiti (MINUSTAH).

The alleged assault took place last February. The day after the incident, the man boarded a flight back to Canada, where he remains.

'Nothing will happen,' lawyer says

Marie Rosy Kesner Auguste Ducena, a lawyer with the Haitian National Human Rights Defence Network, says that even though the alleged victim reported the incident to police, the officer is unlikely to be charged.

"Nothing will happen," she said in an interview with CBC News from her office in Port-au-Prince.

"Women who will go to complain, you will see that maybe somebody will take the complaint and will say to her you will be called after. But in fact, the case will just be closed."

Police officers' impunity

The case is complicated by the fact a police officer was involved — and not a member of the military.

Soldiers can be tried in a military court, but under UN rules, civilian staff — including police officers — cannot be charged in Canada if a crime is committed abroad.  Once back in Canada, they cannot be charged for a crime committed abroad.

It's not known if the evidence in this case is strong enough to have warranted a charge.

Haitian National Police would not say if they are actively investigating the incident. However, authorities in Canada are carrying out an internal review, and the officer could face disciplinary measures.

Wrong message being sent

Over the past six years, there have been 70 reported cases of sexual abuse by UN personnel in Haiti, but not one has ended up in a Haitian court.

"It's the wrong message," said Mark Schneider, the vice-president of the International Crisis Group, which monitors human rights abuses around the world.

"It undermines the integrity of the UN and undermines the ability of the UN to assume and carry out its functions."

Uruguayan soldiers charged

There have been rare exceptions. In 2011, a video showing Uruguayan soldiers sexually assaulting an 18-year-old Haitian man provoked outrage.

Three of the soldiers involved ultimately faced criminal charges in a military court, but human rights groups say that was largely due to public pressure.

The UN's rules must change to provide greater accountability, Schneider said.

"The UN should ensure that in the agreement with the troop-contributing countries, that there is an understanding of what will happen if an abuse occurs — that there will be a full investigation, and that there will be appropriate action taken," he said.