Patents are powerful tools, but they only bite on the materials or methods described in their claims. Or do they?
Two recent appeal decisions show that the monopoly owned by a patent-holder can spill out over the edges of the claims, making life uncertain for those trying to steer a way around them.
The first case (Smith & Nephew v ConvaTec) deals with wound dressings. ConvaTec, an innovative medical products business, has a European patent for a process for applying silver to fibres used in wound dressings. Silver is a known antimicrobial agent, but it can discolour through exposure to light (think photographic film…). The patent offers a solution to this problem with a three-stage method, the last stage involving use of a binding agent at a concentration of ‘between 1% and 25% of the total volume of treatment’.
Smith & Nephew’s planned Durafiber Ag range of dressings were made by a process using a reduced concentration of binding agent – 0.77%.
Of course, you might say, that is outside the patent because it is less than 1%.
You’d be wrong!
The trial judge said Smith & Nephew’s process did not infringe because if you use the rules on significant figures you get to a range of 0.95% to 25.5%. 0.77% is outside that range.
The appeal judges disagreed. They concluded that the right approach was to use rounding conventions, leading to a range of 0.5% to 25.5%. So the Smith & Nephew product did infringe.
So if you are reading a claim with a numerical range in it, you can’t take the straightforward approach that the numbers are the outer limits of the range.
A pinch of salt
The second decision (Actavis v Eli Lilly) looked at a claim for use of a chemotherapy drug, pemetrexed, in combination with B vitamins to alleviate its toxic effects. The claim referred to ‘use of pemetrexed disodium’.
Actavis asked the court for declarations of non-infringement of Lilly’s European Patent (extending to France, Italy and Spain in addition to the UK) on the basis that its product would not be made from the sodium salt. Instead Actavis proposed to use pemetrexed diacid, pemetrexed ditromethamine or pemetrexed dipotassium.
The trial judge and the court of appeal agreed that there would be no direct infringement. But on the question of indirect infringement (supplying a means relating to an essential element of the invention) they differed. Unlike the judge, the appeal court thought that there would be indirect infringement. A doctor using the product would mix it in saline solution. This would mean that both sodium and pemetrexed ions would both be present in the solution. So Actavis’s alternative versions of the product would still infringe.
Fairness v certainty
If you’re puzzled by this you could take a look at the Protocol to Article 69 of the European Patent Convention, which tells us to combine a fair protection for the patentee with a reasonable degree of certainty for third parties. This, together with a series of cases involving anaemia drugs, steel window lintels and hair removing equipment, is how you find the exact borderline of a patent’s claims.
You might end up asking yourself how you can be confident that your product or process is in the clear.