A US federal judge has ruled both Johnson & Johnson’s Cordis unit and rival Boston Scientific are guilty of infringing each other’s patents covering cardiovascular stents, leaving the two firms at an impasse.

The infringement cases cover various stents made at the firms, including Cordis’ drug-coated Cypher (sirolimus) product and Boston Scientific’s rival Taxus (paclitaxel), which together accounted for a global market estimated at $5.5 billion in 2005.

Judge Sue Robinson of the US District Court in Delaware backed earlier jury decisions that Boston Scientific’s stent products infringed upon two patents held by Cordis, dubbed the ‘Gray’ and ‘Palmaz’ patents. But she also maintained an earlier jury ruling that Cordis infringed a patent held by Boston Scientific known as ‘Jang’.

Analysts said both rulings – which can still be appealed – could leave the company found in infringement open to significant damages, but it remains unclear whether either company now has a legal advantage. Boston Scientific also holds another patent known as ‘Ding’ covering drug layering on stents which it claims is infringed by Cypher, but Judge Robinson has not yet delivered a verdict on that case.

Specifically, Judge Robinson ruled that Scientific's Taxus, as well as its Liberte and Express bare metal stents, infringe a Cordis patent covering balloon inflatable stents that expired last year. The jury ruling also held that Liberte infringed a second Cordis patent, which expires in 2016.

She also upheld a 2005 jury verdict that Cordis' Cypher family of coronary stents infringed a Boston Scientific patent covering a stent geometry.

Cordis has said it will appeal that ruling, and any award of damages will have to wait until that appeals process is completed.

- Meanwhile, Cordis said it has filed for approval in the USA to extend the indications for Cypher to include the treatment of in-stent restenosis, based on results of a clinical trial which showed the stent was more effective than in-vessel radiotherapy in preventing this form of re-blockage. The results of the study were published in March in the Journal of the American Medical Association.