Marijuana legalization brought unexpected challenges to Colorado, and it was rarely clear what part of state government was supposed to solve them, or how.

Businesses were selling marijuana-infused, animal-shaped candy attractive to children. Residents growing pot at home were selling it illegally in other states. Growers were applying pesticides to cannabis plants even though none was specifically approved by the federal government for such use.

Enter Andrew Freedman, Colorado’s pot czar, who is bringing together the state’s bureaucracy, marijuana industry, law enforcement community, and public health advocates to fix problems no other state had faced.

Their position on marijuana is hardly the only difference between Canada's prime minister and the president-elect of the United States.

But when Justin Trudeau's government introduces legislation to legalize cannabis this spring, it could spark problems between Canada and the U.S., particularly since Donald Trump has indicated he will keep pot illegal at the federal level.

Here's a look at what could change in Canada-U.S. relations once Canadians start lighting up legally.

Border control

Len Saunders, an immigration lawyer in Blaine, Wash., predicts a boom in his business after Canada legalizes marijuana -- though it's one he has a hard time feeling happy about.

Guam's Governor, Eddie Calvo, who vetoed a bill that would allow eligible residents to grow medical marijuana at home, has proposed legalising recreational marijuana, with heavy taxation.

Mr Calvo said he wants to look at how states navigated into recreational marijuana.

In a written statement he said "let's figure it out and then tax the heck out of it and use those taxes to help fund the hospital, public safety and education."

The Pacific Daily News reports, in his veto message last week for the homegrown medical marijuana bill, the governor stated concerns about the cost of regulating marijuana grown at home.

When Ohio Gov. John Kasich effectively legalized medical cannabis in Ohio, with a stroke of a pen, the state became the 25th in the U.S. to legalize a very comprehensive medical cannabis program. This week the Ohio Board of Pharmacy has rolled out several new sets of rules for the evolving program.  Finally clearing the smoke with Ohio’s medical cannabis program with some sort of focus in rules now proposed for cultivators, doctors who recommend it for patients, and for dispensaries.

Critical op-ed argues that if the industry is actually so nervous about Jeff Sessions, it should oppose his appointment.

On Friday, avid cannabis journalist Alex Halperin published a scathing critique of the pot industry’s post-election posture at Slate. He contends that despite the legal weed sector’s professed anxiety and handwringing over President-elect Donald Trump’s nomination of Sen. Jeff Sessions for U.S. Attorney General, it’s not really doing anything to try and stop it, even though the ballooning industry now has more clout than ever with the political establishment.

On Wednesday, Steven Ognibene had to take the day off from work.

The Rochester surgeon needed to drive three hours to Binghamton because the type of medical marijuana that could help his 11-year-old son, Vincent, wasn’t available locally. It was, though, available at a dispensary in Johnson City, Broome County.

The trip illustrates the obstacles some patients and their families are facing nearly one year after New York allowed for the use of medical marijuana in non-smokable forms for certain conditions.

Another hurdle has been cleared for supporters of legalizing recreational marijuana in Maine.

On Saturday, opponents of the ballot measure legalizing pot conceded to the Yes on 1 campaign. That followed a recount of somewhere between a third and a fourth of all ballots cast in Maine on Election Day.

A lawyer for the No on 1 campaign said it became clear this past week that the results of November's election wouldn't be changed by the recount. He also said many towns and cities in Maine may still consider banning recreational pot use.

With cannabis legalization coming down the pipe in 2017, Premier Rachel Notley said input from Albertans will help set the minimum age to purchase marijuana.

Notley weighed in on weed legalization following a report released by the Task Force on Cannabis Legalization and Regulation recommending a national minimum age of 18 to purchase marijuana. The report also said provinces and territories should be allowed to “harmonize” the minimum age for cannabis with their minimum age for purchasing alcohol and tobacco.

“Not everyone is going to agree, but I think it’s really important that we do engage (with Albertans) because I know lots of families are concerned about safety on (marijuana),” Notley said.

Cannabis activist and his wife, Jodie Emery, were arrested after opening shops in defiance of pot laws.

The man known as Canada's "Prince of Pot" says he's "feeling good" after spending a night in a Montreal jail. 

Marc Emery, who operates an illegal chain of marijuana shops under the name of "Cannabis Culture," was arrested along with nine others on Friday evening during a series of raids by Montreal police. 

Police were targeting six new Cannabis Culture locations that had just opened the day before. 

Emery, who was working at the store on Mont-Royal Avenue, is now charged with drug trafficking, possession for the purpose of trafficking and conspiracy.

"I think the first line of discussion is the individual Maine towns because they're going to have and should have the right to say we don't marijuana here", said Newell Augur, legal counsel for the No on 1 campaign.

The recount was expected to take up to a month to complete and cost taxpayers $500,000. Unofficial results from the secretary of state's office had put the margin of victory at 4,073 in the days after the election. Because the recount was ended early, the final price tag for the recount is expected to be much less. They No on 1 campaign had struggled to provide sufficient volunteers to perform the recount last week, only coming up with eight of the requested ten the state asked for on Wednesday, two days after the recount was to begin.