A poorly written provisional application can have dire consequences for the unsuspecting applicant. A patent application – provisional or not – must meet all the disclosure requirements of Section 112. That is, each application must contain a full and complete enabling description of the invention. Claims are entitled to the benefit of the filing date of the provisional application if they are fully supported in the provisional application. If not, the claims will only be entitled to the filing date of the utility application.
This is particularly important if there is a public disclosure – either before or after the provisional filing date. In the U.S., the public disclosure can be used as a basis for rejection of all claims not explicitly supported in the provisional application if the disclosure is before the filing date of the provisional application.
The problem is even worse in most foreign countries. Many foreign countries do not have a one-year grace period so a public disclosure after the filing date of the provisional application can be used as a basis for rejection of all claims not explicitly supported in the provisional.
Thus, the description of a provisional application should be written just like any other patent application. Use caution when basing a provisional application on a manuscript or scientific article. These tend to describe the invention in very narrow terms with little more than the specific experimental conditions and results. Without more, the provisional application will not be able to support broad claims to the invention and only the narrow embodiments taught in the article will be entitled to the benefit of the provisional filing date. The lesson – a hastily-filed cover page provisional may not protect your foreign rights.
That said, the provisional application can be a very useful tool to provide an additional year of priority at a relatively low cost, particularly when the ultimate end use and market are not fully developed at the time the application is filed. Take the time and effort to fully and completely describe the invention in the provisional application and it will serve you well.