Religion and law
This article will discuss the interaction of the various colleges (pontifical, augural.quindecemviri) during the republic and the Senate.
"When a problem arose concerning the application of a ritual rule, about the material components of a ceremony, or when a public decision affected religious obligations, the authorities fo the Roman state consulted the priests.For cultic purposed they addressed the pontiffs, for divinatory affairs the augurs, as well as the (quin)decemviri, who kept the Sibylinne Books." p. 18
"The priests were consulted by the consuls or the praetors, who were in charge of most public cult, and by the roman senate,whose duty it was to give advice to the magistrates, in particular about religious questions." p. 19
"This shows that Roman priests did not form a separate power. Before giving advice, they needed to be consulted, and their advice could only be enacted by the authority of the magistrate. For cultic purposed they addressed the pontiffs, for divinatory affairs the augurs, as well as the (quin)decemviri, who kept the Sibylline Books." p. 19
John Scheid 'The Formation of Sacred Law in Rome' essay in "Religion and Law in Classical and Christian Rome."