When considering the prior art effect of an alleged public prior use, does it matter how long or how often the invention was publicly visible?  

In decision T 1410/14, the European Patent Office's (EPO’s) Boards of Appeal considered whether an invention involving an articulated rail carriage joint was directly and unambiguously disclosed in the short time in which a test train passed under a publicly accessible railway bridge. They found that there was insufficient evidence, given the circumstances, that the features of the invention were directly and unambiguously disclosed.  

The opposing party argued that the invention could have been derived by observing, from the railway bridge, a relative movement of connected rail carriages. The Board of Appeal considered it not proven that what was observable from the bridge constituted an enabling disclosure of the invention (ie a disclosure that would enable a person skilled in the art to put the invention into effect). The test train travelled at a speed of between 20 and 40 km/h. The relative movement could only have been appreciated while the joint in question was vertically under the bridge and also moving in a relevant manner. A skilled person would have had a time window of less than a second to carry out his observation. Furthermore, it could not be shown that the relevant movement necessarily occurred within the time window at the required location. The appeal was dismissed.  

T1410/14 joins a small but growing body of EPO case law that clarifies the requirements for an alleged prior use to constitute prior art under the European Patent Convention. To remind readers not normally acting before the EPO, the EPO considers the state of the art to comprise everything made available to the public before the priority date of an invention, whether by means of a written or oral disclosure, by use, or in any other way. The EPO’s definition of the state of the art is absolute in that actual access need not have occurred: the mere possibility of lawful public access suffices for a disclosure to belong to the state of the art. However, to destroy novelty, it must be shown that a disclosure was publicly accessible and that the invention was disclosed in a direct and unambiguous manner.   

Already in T1553/06, a decision relating to ephemeral internet links (URLs), it was held that the practical possibility of having access, in order to constitute a disclosure, required that the internet link was live long enough to permit the required direct and unambiguous public access. While T1553/06 was concerned with access to a disclosure, the present decision T1410/14 provides further guidance that also the nature of the disclosure must be considered when assessing its direct and unambiguous character.  

An interesting aspect of T1410/14 was that repeated instances of a theoretical possibility of a public disclosure do not necessarily increase the direct and unambiguous character of a disclosure. It was undisputed that a test train passed under the relevant railway bridge 13 times, each time under similar circumstances. In each instance, it was equally unlikely for the invention to be disclosed in the required direct and unambiguous manner. It remains to be seen whether or not this reasoning would also apply to other scenarios, such as an ephemeral internet link that may be available multiple times.  

T1410/14 acts as a reminder of the importance of keeping an invention secret until a patent application has been filed. In the case, despite the eventual success for the patentee, a great deal of uncertainty could have been avoided by comprehensively preventing public access to the mechanism under test, even if by covering the relevant components of the test train. Effective secrecy may also require that the effect of the invention (in this case, relative movement of connected rail carriages) is concealed if the effect would inevitably reveal the invention.   

Opponents or parties interested in assessing the relevance of prior art should bear in mind that any evidence needs to be more convincing the more serious the issue to be decided. As the EPO’s Guidelines for Examination state, evidence to support a revocation of a European patent will be examined “very critically and strictly”. Where public accessibility to a disclosure is theoretical, ie, conceivable under specific circumstances, clear evidence may be required to show that the specific circumstances occurred in order to demonstrate direct and unambiguous access.