There are only a few reasons why an examiner might reject the claims of a patent application. The reasons are conveniently and thoroughly discussed in four separate statutes (or laws). They are 35 U.S.C. 101, 102, 103, and 112.

Most rejections fit under one of the four general rejection statutes, although they may be used in combination to reject a single application.   As you will see, it is a very complicated system.
We will discuss the four major rejections in detail in the next few sections.  

For now, here’s a brief overview to get you started.

35 U.S.C. 101 deals with the patentability of the invented subject matter. That means if an application is rejected under 35 U.S.C. 101, the applicant will know it was rejected due to a basic flaw with patentability.

35 U.S.C. 102 covers novelty and the statutory bars, while 35 U.S.C. 103 explores the obviousness of the invented subject matter. Finally, 35 U.S.C. 112 delves into problems with the specification.

Of these four statutes, 35 U.S.C. 102 is the most complicated. It's been made even more complicated with the addition of the America Invents Act (AIA) since now there are two sets of 102 laws; pre-AIA and post AIA.  For this reason, 35 U.S.C. 102 will be discussed separately in Module VII. In the current module, we will cover 35 U.S.C. 101, 103, and 112.