A recent decision in the landmark Agence France-Presse v. Daniel Morel case has shown that media organisations cannot claim to hold a license to use, without authorisation from the copyright owner, material such as images sourced from Twitter.

Freelance photographer Morel sued AFP after he found that images of an earthquake he had taken in Haiti were used and distributed by the French news agency without his authorisation and without financial compensation.

While most media organisations verify and ask for permission before publishing user-generated content, some newspapers and magazines don't always play by the rules of engagement confirmed by the Morel ruling, says a leading media law expert.

Last week, the Evening Standard in the UK published an image of a helicopter crash it had sourced from Twitter. The image was shot by a user named Craig Jenner, but, as MediaGuardian reported, the newspaper "could not contact Jenner about its splash" before it went to press.

An Evening Standard source, quoted by The Guardian, added: "All the information about the source of the photo is entered into the database and remains in our library. We've always been of the view whoever took the photo owns the copyright, and if they want payment, there is no question they will be paid."

However, Charles Swan, an intellectual property expert at media law firm Swan Turton, argues that the newspaper was still required to get permission before it used the image. "The difficulty with this is that eye-witness photos will often be 'heat of the moment' material. If a newspaper doesn't get permission before publication it will almost always infringe copyright – being willing to negotiate a fee after the event isn't a defence to a legal claim," he says.

"In most cases the media will get away with this," Swan adds. "Perhaps the tweeter isn't interested in being paid, or the sums involved are too small to make legal action likely. But a policy of publish now, negotiate later cannot be defended from a legal point of view. Copyright isn't just a right to be paid, it's a right to authorise publication."

He continues: "The lesson for professional photographers is clear. Don't rely on the Morel decision. If you tweet photographs you risk them being published without your permission, and if the photograph is a valuable, newsworthy image you will lose out if this happens because your negotiating position will be undermined. Unless that is, like Morel, you are prepared to play hardball."

The Evening Standard's picture desk, as well as Twitter user Craig Jenner, have yet to return BJP's requests for comment.