Most patent attorneys at some point in their career will have been introduced to the “Hand Test”. This is a rule of thumb (well, four fingers and a thumb) test to determine whether a claim is useful. There are various versions, but a familiar one is for Claim 1 of a patent to be printed out – for the sake of argument and objectivity, let’s say in 12 point Times Roman with one-and-a-half spacing – and for a patent attorney (let’s say one taking size 8 in gloves) to try to cover it with their hand laid flat, with fingers together, on the paper over the printed claim. If there are lines of text showing above or below the hand, the claim is generally not infringed by the embodiment of interest, avoidable by one simple workaround or another, or simply impossible to infringe.
While this test is crude, it feels broadly appropriate when applied to some technical disciplines, such as mechanical engineering. It may have less application elsewhere. I’ve seen it used as a principle in setting metrics for patent attorneys – rewards were given for getting independent claims to grant at under a predetermined word length. Chemists did rather well under this system, as a claim such as:
“A composition for use for some purpose or other, comprising:
at least 50% of this stuff;
at least 30% of that stuff; and
no more than 10% of some other stuff”
will often be the best way to characterise the invention, and is usually extremely short. By contrast, in most IT cases the drafting attorney will just have started to define the first functional element of the invention by this point in Claim 1.
It would be good to put the Hand Test to the test, but any objective assessment would require more time than I currently have available. I would however be very interested to know:
(a) the longest claim found to be infringed;
(b) the shortest claim found to be valid; and
(c) more about any study that there may have been considering infringement and claim length.
References, please, not hearsay. There are two word claims found in two US patents – see the collections of patent records thoughtfully provided by others here and here for more details – but I may need a chemist to tell me whether either was valid.
In all these cases, “long” and “short” relate to numbers of words in the claim. For the purposes of effective comparison, it would also be best if only one language was considered at a time – nothing (and no-one) needs many words in technical German. I hope that I’ll be able to provide you with an update on this burning topic in a few weeks.