 Carnap, Lakatos and Hempel all argue that in theory testing we usually implicitly assume an additional premise that states that there are no disturbing factors. Even though in the later literature Hempel’s paper has been taken to be evidence for the existence of cp-laws even in fundamental physics, the issue of whether a cp-clause has to be added as an extra premise in theory testing has to be distinguished from the claim that the laws themselves should be read as containing an implicit cp-clause (for a criticism of this conflation cf. Earman and Roberts 1999, 442ff.; Schrenk 2007a, 25–36; Eliot 2011).