Halifax police are taking a pledge to "start by believing" sexual assault victims when investigating complaints of sexual violence, saying they want to strip away bias and judgment in handling the sensitive cases.

Police Supt. Jim Perrin said Wednesday he was encouraging members of the force to sign the popular social media pledge and use the hashtag .startbybelieving as part of a campaign to make victims of sexual assault more comfortable in coming forward and reporting the crime to police.

"We want to create a climate where you can be comfortable, that when you speak to me I'm not going to judge you," he said in an interview. "I'm going to start by believing you. It's a good reminder to us in policing and it's about being objective and not going into these investigations with biases."

The social media initiative encourages people to sign a pledge stating that when someone reveals they have been raped or sexually assaulted, they will "start by believing" as part of a widespread effort to end the silence around sexualized violence.

Started in the United States in 2011, it involves people signing the pledge, taking a selfie and posting it with the hashtag .startbybelieving.

The Halifax force took it on after multiple Canadian police forces promised to reopen some cases for review in the wake of Globe and Mail coverage of the number of sexual assault cases that were labelled unfounded. The reports concluded that police across Canada close about one in five sex-assault cases as unfounded. That usually means the investigating officer does not believe an act of sexual violence occurred.

In Halifax, the rate of unfounded cases from 2010 to 2014 was 13 per cent.

Perrin said they are looking at the number of unfounded cases in the wake of the report.

Jackie Stevens of the Avalon Sexual Assault Centre said her group continues to hear from people who say they have not had good experiences reporting sexualized violence to police, and that the "start by believing" campaign may hold the force accountable to the public in how it deals with sexual assault cases.

"Many people are used to being blamed or not believed or judged, so I think initiatives like this send a strong message to someone who may be hesitant to report and sends a strong message to people who commit sexual offences because it's saying police will take allegations of sexual assault seriously," she said.

"It also shows that police are recognizing that they have work to do."

Perrin said he acknowledges that sexual assault victims may not report an attack out of fear they won't be believed, will be judged or will be made to feel ashamed. But he says the pledge doesn't necessarily mean charges will be laid as a result of every allegation.

"We can create that climate on the front end, but we can't predict where the evidence is going to take us," he said.