OTTAWA -- It turns out there's not a lot of logic in the belief that it's against the law to Vulcanize Sir Wilfrid Laurier's likeness on the $5 bill.

The death of Leonard Nimoy last week inspired people to post photos on social media of marked-up banknotes that show Canada's seventh prime minister transformed to resemble Spock, Nimoy's famous "Star Trek" character.

For years, Canadians have doodled Spock's pointy Vulcan ears, sharp eyebrows and signature bowl haircut on the fiver's image of Laurier, the first francophone PM.

Contrary to popular belief, it's not illegal to deface or even mutilate banknotes, the Bank of Canada said Monday -- although the publication of a banknote's likeness is still prohibited, except under certain conditions.

There are good reasons to resist the urge to scribble on bills, said bank spokeswoman Josianne Menard.

"The Bank of Canada feels that writing and markings on banknotes are inappropriate as they are a symbol of our country and a source of national pride," Menard wrote in an email.

Long life and prosperity might also take a hit: Menard said disfigured bills risk being yanked from circulation and rejected by retailers.

Following Nimoy's death Friday, social media users posted their own versions of Laurier's Vulcan makeover to honour the actor.

"Spock your $5 bills for Leonard Nimoy," a group called the Canadian Design Resource tweeted alongside its depiction.

Images of the altered bills circulated widely online and attracted international media attention to something many Canadians had never seen before -- although for others, it was hardly a new frontier.

Calgary artist Tom Bagley, who posted his own Spock-Laurier hybrid on Facebook and Flickr after Nimoy's death, described it as an old bar trick to impress the waitress.

He compared the sketches to folding the $20 bill along the Queen's face to make her smile or frown.

Bagley said he had no concerns about any potential legal issues with defacing the banknote. Besides, he said, his sketch was erasable.

"I don't know anyone that's gone to jail for it," he said in an interview.

"I always thought it was OK as long as the numbers were intact -- it still counted as money. That's what I heard. Because stuff happens, like say you spill spaghetti sauce all over it or something like that."

The Mounties said Monday they're aware of the sudden Spockification frenzy, but could cite no police investigation of the defaced notes or the images posted online. An RCMP spokesman referred questions to the Bank of Canada.

Interestingly, the central bank's boss might not have objected.

Stephen Poloz has called Star Trek his favourite TV series, and even referenced the show in a December speech before the Economic Club of New York. That address was titled, "Speculating on the Future of Finance."

"Does anybody besides me wonder what the banking system looks like in the background of Star Trek?" Poloz said in the prepared remarks of his Dec. 11 speech.

The flip side of the latest $5 bill, which bears Poloz's own signature, features images representing Canada's contribution to space exploration, including a picture of an astronaut.

So, will all those Spocked bills be allowed to continue on their mission? Not once they reach a bank, said Menard. Financial institutions would likely return them to the Bank of Canada to be pulled from circulation.

The bank would prefer that people and media outlets stop distributing and publishing images of the defaced bills, she added. The Canadian Press distributed an image of the bill in order to provide a more accurate and complete account.

Interestingly, when it comes to protecting cash in Canada, the law treats coins and banknotes differently.

The Royal Canadian Mint's website says it's illegal to melt down, break up or use any coin that is legal tender in Canada as anything other than currency.