Paul Botley edited, with Dirk van Miert, the correspondence of Joseph Justus Scaliger (8 vols, Geneva, Droz 2012). Scaliger corresponded regularly with Casaubon, and supported him throughout his career. Casaubon published some of Scaliger’s works posthumously as Iosephi Iusti Scaligeri Opuscula varia antehac non edita in 1610, a year after Scaliger’s death. The piecemeal and imperfect publication of Casaubon's letters became apparent while he was preparing Scaliger's letters for the press, and he established this project as a solution.

Máté Vince worked on the religious-political controversy between Catholics and Protestants in the aftermath of the Gunpowder Plot. Casaubon’s first publication after his move to England, the Epistola ad Frontonem Ducaeum (1611), is an important document of the debate, in which Casaubon represents King James’s position on the Jesuits’ doctrine of the Pope’s right to depose princes; a doctrine that, as the correspondence reveals, Casaubon found ‘diabolical’. He thought that the murder of his former patron, Henri IV of France was a direct consequence of this doctrine.