MONTREAL — The new federal government should proceed slowly with changing the country's drug laws, says the Canadian Centre on Substance Abuse, which has released a report on the U.S.'s experience legalizing cannabis.

Representatives with the centre, which is funded by Health Canada, met with officials from the two U.S. states to legalize pot for personal use — Colorado and Washington — to learn about what mistakes to avoid.

Rebecca Jesseman, senior adviser for the centre, said in an interview the Canadian addiction experts were given one key message during their visit south of the border: Take your time.

"They said to start incrementally and don't move too quickly," on marijuana legalization, she said. "And make sure your decisions and your actions are informed by the best possible evidence available because there are going to be unanticipated consequences."

Colorado learned that lesson while trying to regulate non-smoked marijuana products, known as edibles.

Authorities quickly realized that while the state regulated the amount of marijuana allowed in...