Provisional patent applications, or "provisionals," have grown in popularity since their introduction in the U.S. in June of 1995. Although provisionals, when used properly, can be valuable tools in the development of a patent estate, they also can be seductive traps for the unwary.

Provisionals offer certain advantages over non-provisional or regular utility patent applications. For example, (i) a provisional does not need to be as formal as a non-provisional patent application and thus can be easier and cheaper to prepare, (ii) its filing fees are significantly less than those of a non-provisional patent application and (iii) under certain circumstances, its filing date may not be taken into account when calculating patent term. The last advantage can be significant, for example, in the case of patents covering pharmaceuticals, where it is desirable to have the longest possible patent term.

It is important to note, however, that provisionals are not examined substantively by the U.S. Patent and Trademark Office (PTO). Furthermore, they lapse one year after their filing date. Two approaches exist if an applicant wishes to obtain patent protection for an invention described in a provisional. The first approach is to convert the provisional into a non-provisional patent application, which is then examined by the PTO. This approach usually is not recommended because the filing date of the provisional is used to calculate the expiration date of the patent that ultimately issues. As a result, a patent owner may sacrifice up to one year of patent term using this first approach. The second and more commonly used approach is to file a non-provisional patent application that claims the benefit of the filing date of the provisional. Regardless of which approach is used, a hidden danger exists in that the description of the invention provided in the provisional must meet the statutory requirements for a non-provisional patent application and provide adequate support for the claims that eventually issue in a patent. Failure to comply with the statutory requirements may result in the loss of the benefit of the earlier filing date of the provisional.

The Court of Appeals for the Federal Circuit exposed the danger that may arise from an inadequate description in a provisional in New Railhead Manufacturing vs. Vermeer Manufacturing and Earth Tool. In this case, the Court affirmed a lower court's finding that the patent at issue was not entitled to claim the benefit of the filing date of a provisional. Consequently, the Court held that the patent owner's sale of its own product less than one year before the filing date of the provisional application but more than one year before the filing date of the non-provisional patent application constituted a statutory bar to patentability, thus rendering the claims of the patent invalid. In its decision, the Court stated that the "written description of the provisional application must adequately support the claim of the non-provisional application." The Court went on to add that "the specification of the provisional must 'contain a written description of the invention and the manner and process of making and using it, in such full clear, concise, and exact terms' … to enable an ordinarily skilled artisan to practice the invention claimed in the non-provisional application." In its reasoning, the Court affirmed the lower court's decision that the provisional failed to describe a particular element of the invention and thus did not adequately support the invention ultimately claimed in the patent.

The practical implication of this recent decision is that one should not assume that the filing of a provisional will preserve patent rights to an invention. Because of time constraints, it sometimes may be necessary to prepare and file a provisional quickly using just the information at hand (such as a slide presentation, business plan, or soon to be published scientific article) to preserve patent rights. To the extent that time permits, however, the applicant should attempt to identify the invention and its commercial significance, formulate patent claims that cover the invention, and then craft adequate written support for the claims. Without such analysis, there is greater risk that the claims that issue from a non-provisional patent application claiming the benefit of an earlier filed provisional will not be adequately supported by the description in the provisional. The result for the applicant may be loss of a priority date which, in circumstances like those described in New Railhead, could render the resulting patent invalid.

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