Patent officials made the decision after some information came to light that was not considered when the patent was originally granted, according to a statement from the Patent and Trademark Office.
With the new information, patent officials need to determine whether the software fix is genuinely new, and not an obvious fix--key criteria for awarding patents, according to the department.
As previously reported, aircraft manufacturer McDonnell Douglas received the patent for a software technique called "windowing" that is used to correct computer code that could be affected by the year 2000 glitch. The company handed the patent over to the software's inventor, Bruce Dickens.
Dickens, now president of a company called Dickens2000, said he will license the patent for an up-front fee and subsequent royalty payments. After the date change, licensing fees will increase substantially for firms that don't agree to the initial offer.
Bill Cray, a lawyer representing Dickens from the California-based law firm Levin and Hawes, said his client appreciates the patent review. "Bruce welcomes the opportunity to re-examine this, to clear up all the squabbles going on. This is an opportunity to strengthen his patent."
Experts say decisions by the PTO to review patents that are already approved are rare.
"Patent reviews are rare if not non existent," Giga Information Group Kazim Isfahani said.
Jeffrey Neuburger, a patent law attorney at New York-based Brown, Raysman, Millstein, Felder & Steiner, said there is a 50-50 chance that the PTO will narrow or overturn its original decision.
"But if they do re-examine and reaffirm the patent, then the patent is very, very strong," Neuburger said.
Windowing is the most popular of several techniques used to allow software to recognize a year as a four-digit field. A typical windowing fix ensures years entered as 00-29 represents 2000 through 2029, and years entered as 30-99 represent 1930 through 1999.
Dickens' attempt to collect fees and royalties from companies could deal a financial blow to thousands of firms. Analysts say that roughly 90 percent of Fortune 500 firms have used some form of windowing to fix their computer systems.
"I know of a number of industry groups who have stated their concern about the patent," Isfahani said.
The Dickens windowing patent was issued in 1998. Analysts have discovered information on the fix from IBM, which referred to the technique in pamphlets as far back as 1991.
Isfahani said there is overwhelming evidence in the industry that windowing was used on a widespread basis as far back as 1990. "The fact that the Patent Office is re-examining the patent is indicative" that the office could change its earlier decision, he added.
With just nine days left until the date change, Isfahani said the decision to re-examine the patent was a good one. "It needs to be now decided either way so organizations know what to expect," he said.
The Patent Office did not disclose a time frame for the re-examination process and government officials could not be reached for comment.