Apple's case to restrict the rights of bloggers to report on what the company does reaches another key date this month.

The company is scheduled to show up at an April 20 hearing in the California Court of Appeal. The appeal is being mounted by the Electronic Frontier Foundation (EFF) on behalf of PowerPage publisher, Jason O'Grady.

The EFF will argue that a previous decision erred when it refused to protect O'Grady's emails and unpublished materials.

Apple had pursued O'Grady, Think Secret and Apple Insider over a leaked rumour of a product that has strangely never shipped, called Asteroid.

Industry-watchers believe the court's decision to uphold Apple's complaint - which alleged that product information leaks were not in the public interest - is a threat to the rights of all journalists to protect their sources.