Additional Protocol II and threshold of application

As it is well known, Additional Protocol II (AP II) does not apply to all and every armed conflict of a non-international character: rather it sets a threshold of application, below which internal armed conflicts remain merely subject to the provisions of Common Article 3 (CA 3) to the Geneva Conventions (GCs). The definition of the threshold of application of AP II, however, does not solve all problems: inasmuch as the content of AP II corresponds to customary international law (CIL) the problem subsists, whether or to which extent CIL rules are conditioned by the same threshold of application. The present contribution will, therefore, be divided into two parts: in the first part, I will endeavor to define the threshold of application of Additional Protocol II (AP II); in the second part, I will try to tentatively answer the question on whether and to what extent the precise identification of this threshold really matters, when we consider the situation under the lens of CIL.