Abstract. In the previous paper, we have characterized (joint) subnormality of a C0-semigroup of composition operators on L 2 -space by positive definiteness of the RadonNikodym derivatives attached to it at each rational point. In the present paper, we show that in the case of C0-groups of composition operators on L 2 -space the positive definiteness requirement can be replaced by a kind of consistency condition which seems to be simpler to work with. It turns out that the consistency condition also characterizes subnormality of C0-semigroups of composition operators on L 2 -space induced by injective and bimeasurable transformations. The consistency condition, when formulated in the language of the Laplace transform, takes a multiplicative form. The paper concludes with some examples. [21] proved that a C 0 -semigroup of subnormal operators is automatically jointly subnormal and as such has an extension to a C 0 -semigroup of normal operators. As noted below, this is still true for C 0 -groups of subnormal operators (cf. Proposition 2.1). Itô's theorem enabled Nussbaum [29] to prove the subnormality of the infinitesimal generator of a C 0 -semigroup of subnormal operators. The interested reader is referred to the monograph [7] for the foundations of the theory of subnormal operators.Composition operators, which play an essential role in ergodic theory, turn out to be interesting objects of operator theory. The questions of bound-