One of the lesser-known requirements for a patent is that it must claim a “definite” invention. The issue of definiteness lies primarily with the patent draftsperson, often a patent attorney or agent that is hired to expand the scope of an invention as broadly as possible without crossing the line into indefiniteness. Nevertheless, as patent litigation continues to develop, alleged infringers are growing ever wiser that claims can be invalidated for stretching too far, rendering them indefinite. On June 2, 2014, the Supreme Court issued its decision in Nautilus, Inc. v. Biosig Instruments, Inc., relaxing the standard for a court to find a patent claim invalid as indefinite.
By statute, the definiteness requirement mandates that each patent must “conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as [the] invention.”  Courts have struggled throughout the years to balance the inherent limitations of written language with the need to limit the monopolistic rights granted through a patent for a clear invention. In so doing, Courts have mandated that the notion of definiteness is to be evaluated in light of the specification (the written description of the invention) and prosecution history from the perspective of a person skilled in the relative art at the time the patent was filed.
For over a decade, the Federal Circuit has erred on the side of validity for claim definiteness, questioning whether patent claims were “amenable to construction” or “insolubly ambiguous.” Under these guidelines the Federal Circuit would hold that “if reasonable efforts at claim construction result in a definition that does not provide sufficient particularity and clarity to inform skilled artisans of the bounds of the claim, the claim is insolubly ambiguous and invalid for indefiniteness.”  The United States Patent and Trademark Office interpreted this standard to mean that “the validity of a claim will be preserved if some meaning can be gleaned from the language.” 
That standard is no more. In Nautilus, the Supreme Court held that the concepts of “insolubly ambigu[ity]” and “amenab[ility] to construction” are not apt standards for definiteness. The Court sought to mandate clarity of patent claims, while recognizing that absolute precision is unobtainable. Under this reasoning, the Court returned to traditional notions, holding that a patent is invalid for indefiniteness if its claims, read in light of the patent’s specification and prosecution history, fail to inform, with reasonable certainty, those skilled in the art about the scope of the invention.
It can be noted that the Nautilus decision does not create any breakthroughs in patent invalidation. In reality, the Supreme Court rendered no new standard as it returned to a more barebones, traditional approach to the definiteness standard. Rather, the decision lessens the burden for patent and patent claim invalidation for lack of definiteness and acts as a subtle hint to the Federal Circuit and lower courts that a definiteness challenge shouldn’t necessarily err on the side of validity. Thus, the decision opens the gate for further validity challenges based on indefinite claims.
 35 U.S.C. 112, Paragraph 2
 Star Scientific, Inc. v. R.J. Reynolds Tobacco Co., 537 F.3d 1357, 1371; see, also. ExxonResearch & Eng'g Co. v. United States, 265 F.3d 1371, 1375 (Fed. Cir. 2001) (“Only when a claim remains insolubly ambiguous without a discernible meaning after all reasonable attempts at construction must a court declare it indefinite.”)
 See, MPEP 2173.02