The Federal Circuit's recent decision in Dynamic Drinkware confirms that the US patent system applies a very unique rule to the prior art effect of provisional applications. Following-up the Giacomini decision, the Federal Circuit confirmed that for the provisional application to be effective as prior art, not only does there need to be a follow-on non-provisional application claiming priority to it, but the claims of that follow-on application must be supported by the provisional application. In Dynamic Drinkware, the issue was that the provisional application had disclosure that was also included in the non-provisional filing. However, the claims of the non-provisional, directed to other (irrelevant) additional disclosure created a fatal defect as to the prior art effect of that disclosure.
While scholars will doubtlessly debate the propriety of the rule and result, patent practitioners should immediately realize the potential uses of this decision. When an examiner is citing a reference and relying on a provisional filing date, not only must the relevant disclosure be in the provisional application and carried through to the non-provisional application, but so too must the claims of the non-provisional application have proper priority, even if the particular disclosure missing for proper claim support has nothing to do with the disclosure being relied-upon for prior art purposes.
Some interesting issues will no doubt follow from this case. Does this rule require that all of the claims have priority to the provisional for the provisional to be effective, or does priority of only a single claim suffice? The Federal Circuit appears to presume that it is the claims (plural) that must be supported. For example, the Federal Circuit explains that Dynamic must "demonstrate support in the  provisional application for the claims of the  patent." (emphasis added).
In comparing this approach to the prior art rules of other jurisdictions, a very different result may be achieved. For example, in other jurisdictions, it is the the continuity of disclosure that enables an application claiming priority to an earlier filed application to be used as a prior art sword in a prior art attack as of the date of the earlier filed application, irrespective of whether or not the later filed claims have support.