A lawyer says internet service providers offering the GlobalMode service, which allows customers to access blocked overseas content, are probably in breach of copyright laws.
Sky Television, TVNZ, MediaWorks and Lightbox are taking legal action against CallPlus and Bypass Network Services for offering the service.
Intellectual property lawyer Kate Duckworth said although services like GlobalMode can be used legally, it was likely most of the available content infringes copyright.
"The copyright owners own the rights, and they haven't authorised this particular access to it - they're bypassing the official routes, and accessing it elsewhere, so it's basically copying without the right to do so."
Ms Duckworth said people cannot assume all online content is legal to access, and customers who use this service could well be acting illegally.