In a ruling in Astron Clinica and others' Applications on January 25, Mr Justice Kitchen said that where claims to a method performed by running a suitably programmed computer or to a computer programmed to carry out the method are allowable then, in principle, a claim to the program itself should also be allowable.

The UK IPO has decided not to appeal that decision. But as a result of accepting the ruling, the Office has had to change its policy on the patenting of computer-implemented inventions.

Yesterday it issued a revised practice note clarifying what claims will be allowed in a patent application.

Gareth Fennell, a partner at Kilburn & Strode, said that the IPO's new practice brings the UK back in line with the European Patent Office and should be welcomed by patentees of software.

The decision means that patent applicants will be able to claim protection for the carrier (for example, a compact disc) on which the computer program is stored, if the use of that program is itself patentable.

"Overall, the decision recognizes the commercial needs of patentees," Fennell said. "Without this change, IP owners had to rely on contributory infringement rules to prevent people from copying their invention onto a CD. Now an IP owner will be able to sue for infringement if someone makes a copy of it."

But the UK IPO made it clear that if protection for carriers is to be available, then the claim to the computer program must be drawn to reflect the features of the invention that would ensure the patentability of the method which the program is intended to carry out when it is run.

"Where, but only where, these conditions are met, examiners will no longer object to claims to a computer program or a program on a carrier," says the new practice note.

Fennell said that he would now advise clients who have software-related patent applications pending examination at the UK IPO to amend their applications to include the new claim.