The Court of Appeals for the Federal Circuit held that the work of co-inventors that was performed separately and was publicly disclosed before conception of the claimed invention can constitute joint inventorship where all of the inventors collaborated at some point prior to disclosure.
According to the Federal Circuit, "a collaborative enterprise is not negated by a joint inventor disclosing ideas less than the total invention to others, especially when, as here, the collaborators had worked together for around one year prior to the disclosure, and the disclosure occurred just a few weeks prior to conception. Inventorship of a complex invention may depend on partial contributions to conception over time, and there is no principled reason to discount genuine contributions made by collaborators because portions of that work were published prior to conception for the benefit of the public. Earlier publication of an invention is obviously a potential hazard to patentability, but publication of a portion of a complex invention does not necessarily defeat joint inventorship of that invention, and it does not here."
Read the case here.