Definition of Fencing patents
Patents procured in an effort to broaden the scope of the invention beyond the article or process which is actually intended to be manufactured or licensed. Special Equipment Co. v. Coe, 79 U.S.App. D.C. 133, 144 F.2d 497, 499.
That's the definition of Fencing patents in Black's Law Dictionary 6th Edition. Courtesy of Cekhukum.com.