Until passage of the Leahy-Smith America Invents Act (AIA), interference proceedings were a unique and important feature of the U.S. patent system. Interferences were declared when two different parties filed a patent application claiming the same invention.

In addition to relying upon the filing date of their patent applications, the parties could submit research records and testimony of inventors and corroborators in an effort to show that they were first to invent. No other patent system in the world used interferences. Instead, most countries have a first-to-file system, where a dispute between parties filing patent applications claiming the same invention is generally resolved by looking at who has the earliest filing date.

Under the AIA, the U.S. will move to a modified first-to-file system and interference proceedings will eventually be eliminated. But, interferences have not yet disappeared. The first-to-file law will not go into effect until March 16, 2013, and even after the first-to-file provisions become effective, the new law only applies to patent applications and patents with an effective filing date on or after March 16, 2013.

According to the Patent and Trademark Office (PTO), an application filed before that date would not be subject to the first -to-file provisions. The application will be treated under the first-to-invent provisions of the law in effect on Sept. 15, 2011 (before the enactment of AIA).

So, pending U.S. patent applications and issued patents may be subject to the interference laws for some time to come. There is, however, a provision in the AIA— section 6(f)(3)(A)) —that requires the PTO to issue regulations regarding the procedures under which an interference commenced before the effective date is to proceed. The PTO was given the options to dismiss the interference without prejudice to the filing of a petition for post grant review or to proceed under the old rules.

It appears that the PTO has opted to go with the latter option. The proposed rules issued in early February  indicate that interference proceedings will continue to be governed by the prior interference rules regulating contested cases and interferences, which will remain in effect so as to not disrupt ongoing interference proceedings.

Additionally, even after interferences become obsolete, one component of them will remain in a modified form: derivation proceedings. The new derivation proceedings were created to ensure that the first person to file a patent application is actually the true inventor. New rules have been proposed for these derivation proceedings and they will be conducted in a manner similar to the inter partes reviews and post grant reviews also introduced under the AIA.