Can a material be considered a valid prior art reference if it pertains to an inoperative device?

A material can indeed be considered a valid prior art reference even if it pertains to an inoperative device because it contributes to the body of knowledge in the field. In the context of patent law, prior art can include any evidence that the invention was known or used before the patent application was filed, as long as it is publicly accessible. This encompasses not only patents and published literature but also documents that may describe devices—even if those devices are not currently functional.

The relevance of a reference pertains to its availability to the public rather than its operability. If a device has been published and documented, it therefore becomes part of the literature that the patent examiner must consider in evaluating the novelty and non-obviousness of a new invention. In essence, the primary consideration for prior art is whether the information is accessible and teaching the public about the invention or concept it encompasses.