Online identity theft, or falsely using someone else's personal information, has previously been legal unless it was proven to cause defamation of character.
The legal change that steps into effect from September 4 is the result of a European Union directive on cyber crime that required Finland to change its laws.
Under the new legislation acts such as updating someone else's Facebook profile will be considered a form of identity theft. The text of the new statute is worded so that a fine will ensue if one causes financial injury, defamation or "greater than a minor inconvenience" to someone online.
Even relatively frivolous acts such as creating a fake social media profile will become a misdemeanour when the new statute kicks in. Failure to remove such profiles in spite of official complaints can constitute a "more than minor inconvenience" from September.
Sergeant Marko Forss of the Helsinki Police welcomed the change saying it provides much-needed clarifcation.
"The positive thing is that it clarifies the position of the parties involved so that when someone clearly assumes the identity of another, it is a punishable offence and there is no need to wonder if it’s a case of fraud or defamation or some other crime," Forss explained.
According to the police, the new law is designed to send a moral message rather than result in litigation.