The Ides of March in the coming year should be heeded by all patent filers. March 15, 2013 is the last day on which an application can be filed in the U.S. without the risk of being examined under new rules that greatly expand the prior art that can be cited against the application.

Patent applications filed the next day, March 16, 2013, and thereafter, will be examined under the America Invents Act (AIA), which changes the U.S. to a first-inventor-to-file system. (We earlier reported on the key changes that the AIA introduces to our patent system.)

The changes made by the AIA affect entirely new filings but may also affect conversions from a provisional application to a regular (nonprovisional) application.

To avoid the effects of this landmark shift in the patent law, a patent application with any new subject matter must be filed by March 15, 2013. An unprecedented surge of new filings is expected that day and in the weeks preceding it.

Why the urgency? Under the AIA, for prior art purposes, any published U.S. patent application based on a foreign application will speak as of the filing date of its foreign counterpart for all subject matter that was in the foreign counterpart. Under present law, the content of such a foreign application first counts as prior art only when the U.S. application gets filed, typically up to a year later.

In other words, as soon as the AIA goes into effect, a large number of foreign applications will instantly become prior art up to 12 months earlier than under present law.

That is not all. Under present law, a publication up to a year before the filing date of an application can be avoided as prior art if the inventor shows that he invented before the publication date.

Under the AIA, such a showing is not permitted, and all third-party publications before the application filing date immediately become unavoidable prior art, unless the inventor happens to be able to show a prior publication, by or through the inventor, of this subject matter.

Similarly, a third-party patent application filed ahead of a given application will not be able to be sidestepped under the AIA by showing prior invention; such a third-party application will immediately become unavoidable prior art unless the inventor can show a prior publication by or through the inventor of this subject matter.

The only way to avoid this onslaught of new prior art is to be on file on or before March 15, 2013. This date looms so large that we expect the period from January 2 through March 15, 2013 to be frenetic for patent filers. Plan now! File early! Our patent practitioners will be working with our clients to make strategic filings ahead of this deadline.

Would Julius Caesar have avoided his fate had he been on file before the Ides of March? We do not know. But our readers who have planned for the Ides of March 2013 will be ready for this fundamental shift in the patent law.