In Itinere
Black's Law Dictionary · Henry Campbell Black, M.A. · 1910
Black's Law Dictionary
In eyre; on a journey or circuit. In old English law, the justices in itinere (or in eyre) were those who made a circuit through the kingdom once in seven years for the purposes of trying causes.
3 Bl. Comm. 58.
In course of transportation; on the way; not delivered to the vendee. In this sense the phrase is equivalent to "in transitu."