A provisional application only protects its filing date for what is properly disclosed in the provisional application. In D Three Enterprises v. Sunmodo Corp. (Federal Circuit, May 21, 2018) (Slip Opinion) the disclosure of a provisional application was found to be insufficient under Section 112(a) and the asserted patent claims were invalid. I summarize just one aspect of this case. The plaintiff had filed a provisional application in February, 2009 and later non-provisional applications that matured into some U.S. patents. The plaintiff then sued some businesses for allegedly infringing claims of these U.S. patents. At least one of these businesses was selling allegedly infringing products as early as June, 2009 -- after the filing date of the provisional application but apparently before the filing dates of the plaintiff's non-provisional applications. Since these allegedly infringing products were apparently in the marketplace (e.g., in public use) before the filing dates of the plaintiff's non-provisional applications, they could be used to invalidate the patent claims of the U.S. patents that had grown out of the non-provisional applications (i.e., these products were intervening prior art). Therefore, to avoid having its patent claims invalidated, the plaintiff had to rely on the written description of its February, 2009 provisional application. But that disclosure was found wanting. The Federal Circuit held that the provisional application only disclosed a single type (e.g. embodiment) of washerless assemblies with a specific W-pronged attachment. This specific disclosure of a single embodiment of washerless assembly with a specific W-pronged attachment was held to be insufficient written description support under Section 112(a) for patent claims reciting broader scope that included washerless assemblies with other types of attachments. The asserted patent claims were therefore invalid. This is a case where the Federal Circuit found that the broad scope of the patent claims was not supported by the narrow disclosure of the provisional application. In the above case, if the provisional application had disclosed two or three embodiments of washerless assemblies with different attachments, the result might have been different. Therefore, whether drafting a provisional or a non-provisional patent application, it is good to give thought to different types of embodiments that might be disclosed. And a provisional application only holds its filing date for what it properly discloses (e.g., what it discloses consistent with the requirements of Section 112(a)).
Doing patent applications for a flat fee makes a lot of sense. In setting the fee, the practitioner looks initially at the complexity of the invention. Another variable, is the number of embodiments. The number of embodiments is a delicate area because in general, as a practitioner, you want to encourage an inventor to disclose a reasonable range of embodiments. All of the above means that the practitioner must conduct at least a partial interview before being able to quote a flat rate. The practitioner also needs to provide some legal advice about the desirability of having a reasonable number of embodiments, and not limiting the disclosure to a single embodiment.
A flat fee automatically takes the practitioner's efficiency, experience and skill into consideration. The practitioner should set the fee within the range that the practitioner believes would typically be charged by other practitioners of similar experience and skill for drafting a patent application of similar complexity. If a practitioner is inefficient and takes more than the usual number of hours for such an application, then the practitioner must absorb the hardship of working more hours for less money. On the other hand, if the practitioner is more efficient that the average patent attorney, then I can see no reason why the practitioner should not receive that benefit.
What the flat fee does is it allows a fee to be set taking into consideration a range of considerations, including all of the considerations required by USPTO and state bar ethics rules regarding avoiding excessive fees. Not all of those considerations are discussed here. I have discussed the ones I feel are most pertinent.
A flat fee benefits the client by providing predictability to the cost of the preparation of a patent application. I think a lot of the complaints about fees in the legal profession stem from cases where billing by the hour leads to unexpectedly large fees.
There may be case where a flat fee is not practicable. If the complexity of the application and the scope of the invention are not clear, then it may not be practicable to set a flat fee. But, those are probably the exceptions.