What is the difference between reexaminations ordered under 35 U.S.C. 304 and 35 U.S.C. 257?

The MPEP distinguishes between reexaminations ordered under different statutory provisions:

1. Reexaminations ordered under 35 U.S.C. 304:

• These are standard ex parte reexaminations
• The certificate states “Reexamination Request” before the filing date and number
• They continue an established ordinal numbering sequence

2. Reexaminations ordered under 35 U.S.C. 257:

• These result from a supplemental examination proceeding
• The certificate states “Ex Parte Reexamination Ordered under 35 U.S.C. 257”
• The certificate states “Supplemental Examination Request” before the filing date and number
• They have a separate and new ordinal sequence, beginning with “(1st)”

The MPEP notes: If the reexamination proceeding was ordered under 35 U.S.C. 257 as a result of a supplemental examination proceeding, the certificate is also titled “Ex Parte Reexamination Certificate.” In addition, the certificate will state “Ex Parte Reexamination Ordered under 35 U.S.C. 257”.

To learn more:

• Ex Parte Reexamination
• Supplemental Examination
• USPTO
• Patent Law