Chapter 3 – Patentability
3.4 Inventive step
3.4.001An invention is held to involve an inventive step if it is not obvious to the skilled person in the light of the state of the art (which does not include prior rights, see points 3.3.003-3.3.004). In assessing inventive step as opposed to novelty (see point 3.3.001), multiple sources of prior art may be applied.
The inventive step requirement is intended to prevent exclusive rights forming barriers to normal and routine development.
3.4.002The EPO seeks to make a realistic and balanced assessment of the inventive step criterion. Inventive step is usually evaluated on the basis of the "problem/solution" approach, in other words whether the solution presented to the problem in the patent application is obvious or not to the person skilled in the art.
GL G‑VII
This always depends on the specific circumstances of the case. Depending on the situation, various factors are taken into account, such as the unexpected technical effect of a new combination of known elements, the choice of specific process parameters within a known range, the difficulty the skilled person has in combining known documents, secondary indicia such as the fact that the invention solves a long-standing technical problem which there have been many attempts to solve, or the overcoming of a technical prejudice.
If you need more detailed information, you are advised to refer to the Guidelines for Examination and to the decisions of the boards of appeal (see point 2.1.002).