The fact that exhibiting a product on a trade fair implies the risk of a first infringement used to be undisputed in the good old days.
In April 2010, the Federal Supreme Court (BGH) has overturned this case-law and issued a ruling (Pralinenform II - I ZR 17/05 according to which the mere fact of exhibiting a product on a trade fair in Germany does not imply the statutory presumption that the exhibitor intends to sell the product in Germany.
The ruling related to trademarks and the generalization to other intellectual property rights is under dispute.
A recently published decision of the Frankfurt Upper District Court has apparetnly disregarded the BGH decision under 6 U 157/09 in a case relating to the well-known Stabilo-pens by putting the burden of proof for the intention not to sell the product in Germany to the alleged infringer.
The Mannheim District Court (29.10.2010, 7 O 214/10) was apparently a little more up to date by ruling that the mere fact of exhibiting a product infringing a patent was not sufficient to prove the alleged infringer's intention to sell the product in Germany with a degree of certainty sufficient to grant a preliminary injunction.
For the practice, it is higly advisable to provide evidence not only for the exhibition of an infringing product but also for the alleged infringer's intention to sell the product on the German market.