How do I - search to determine if there is/was a reexamination for a patent?

Retrieve the patent information from Public or Private PAIR by using the Patent Number search option. Then, select the "Continuity Data" tab or search option, and review the "Child Continuity Data." If a reexamination was requested for the patent or was ordered at the initiative of the USPTO, and is pending or concluded, then the reexamination proceeding(s) will be listed in the Child Continuity Data section and may be identified by the Control Numberdefinition of the reexamination proceedingdefinition, which begins with "90" or "95", i.e., 95/000,000. Select the Control Number link to view information regarding the reexamination proceeding, such as the current status of the proceeding.

Reexamination proceedingsdefinition may also be searched directly in PAIR by using the Control Numberdefinition search option.

For additional information on reexamination proceedings, you may wish to review Patent Official Gazette Notices, or contact the Office of Patent Legal Administration, Central Reexamination Unit at (571) 272-7703.

USPTO FAQ - Questions and Answers (12DEC2006)