What is, or is not, patentable is determined by national law. However, all patent systems, to some extent require:

• novelty;

• inventive step;

• industrial applicability.

In addition, many patent systems, such as those in European countries have exclusions from patentability for certain fields.

Novelty and inventive step

To be patentable, an invention must be novel and also involve an inventive step at the time of filing. In the UK and Europe, the requirement of novelty is absolute. The invention must not have been published –made available to the public in verbal, written form, by use or in any other way – anywhere in the world before the initial patent application is filed.

A disclosure made under a duty of confidentiality is not generally considered a publication for the purposes of novelty.

Publication depends on whether the public is free and able to identify how the invention works. 

For an invention to have an inventive step in Europe, it must not be obvious to a skilled person having regard to the state of the art. In other words, to be patentable, an invention must not be obvious to someone who is skilled in the particular technology of the invention in the light of everything that was publicly known before the date on which the patent application was filed. 

The skilled person is assumed to have read all the relevant materials available but is not expected to be imaginative or inventive. An invention is obvious only if it follows plainly or logically from what has gone before. The nature of the problem solved, how the problem had existed, whether large numbers of people were seeking a solution and whether alternative solutions are available are all relevant when assessing inventive step. Only the prior art teachings available before the invention are considered for inventive step in Europe. Hindsight is an unfair test and is not applied.

Industrial applicability

This criterion is usually used to exclude ‘impossible’ inventions such as perpetual motion machines. In this context the term ‘industry’ includes agriculture.