The dangers of describing/characterizing the prior art

It is usually a very dangerous endeavor for a patent applicant to characterize the prior art, provide any drawings labeled as "Prior Art" within his disclosure, or to otherwise explicitly state what "the invention" is. These statements should be viewed as "ammunition" that you are essentially giving away for free to both the United States Patent Examiner reviewing your case, and also to any future alleged infringers that you bring an infringement action against. Both parties will use your own statements/figures to shoot down your patent application or otherwise invalidate your issued patent.  Poly-America, L.P. v. API Industries, Inc., No. 2016-1200 (Fed. Cir. 2016) is one such cautionary tale (although note that there are countless other tragic stories just like this one).

A more detailed analysis of this case can be found at Carter Deluca:

http://www.cdfslaw.com/publications/protecting-claim-scope-lessons-poly-america-l-p-v-api-industries-inc/