According to the case law of the boards of appeal enhanced effects could not be adduced as evidence of inventive step if they emerged from obvious tests (T 296/87, OJ 1990, 195; T 432/98, T 926/00, T 393/01).
In T 308/99 the claimed use was based on a thoroughly obvious property of known substances. The slightly enhanced effects associated with the claimed use in comparison with substances used in prior art emerged from obvious tests.
Work involving mere routine experiments, such as merely conventional trial-and-error experimentation without employing skills beyond common general knowledge, lacked inventive step (T 455/91, OJ 1995, 684; T 104/92).
In T 253/92 the subject-matter of claim 1 related to a process for the manufacture of a permanent-magnet alloy. In the board's view, a skilled person would have regarded it as obvious to try out a variety of alloys known from the prior art to be of similar composition to those of the better examples and to measure their magnetic properties.
In T 423/09 the board stated that the enhanced effect did not emerge from routine tests but from the practice to be followed according to the rules and recommendations of the handbook. The skilled person following the recommended practice prescribed in this handbook, and thus acting only routinely would inevitably obtain this enhanced effect, which therefore could not be taken as an indication of inventive step.