Just to add a little to what BK said in his post - I was perusing the Manual of Patent Examining Procedure Revised Feb 2003, put out by the U.S. Department of Commerce. This is the so-called rule book for Patents. LoanRangers question, like so many, does not just jump out with a clear cut answer because the question is never asked that way in the manual. But an answer does emerge from related material. So, here are a few excerpts that get to the point:
Page 2200-69 section G. Claim Interpretation and Treatment: "original patent claims will be examined ONLY on the basis of prior art or printed publications applied under the appropriate parts of 35 U.S.C. 102 and 103. .... (In re Yamanmoto, 740 F.2d 1569,222 USPQ 934 (fed.Cir.1984)).In a reexamination hearing involving claims of an expired patent, which are not subject to amendment, a policy of narrow construction should be applied. Such a policy favors a construction of a patent claim that will render it valid; i.e., a narrow construction, over a broad construction that would render it invalid.
In the original text the word ONLY is italicized for emphasis but I couldn't figure out how to do it on the IHUb site so I made it caps. We know expired patents are printed material so they are prior art but so are unexpired patents. In other words, expiration is irrelevant.
I included the Yamanmoto ruling because there has been discussion in some posts about the narrowness, i.e., limited number of conditions outlined in the application. This case may have something to do with it. Narrow is good where prior art exists.
Page 2200-67 section B. Matters other Than Patents or Printed Publications. "Rejections will not be based on matters other than patents or printed publications, such as public use or sale, inventorship, 35 U.S.C. 101, fraud, etc.... A rejection on prior use or sale, insufficiency of disclosure etc. cannot be made even if it relies on a prior patent or printed publication.
In other words, it has to rely on just a patent or prior publication. Expiration of a previous patent and everything else are not considered in accepting or rejecting the claim.
For what its worth. Now, I need to go find some other obtuse regulation to read.
