debet et detinet

DEBET ET DETINET, pleading. He owes and detains. In an action of.debt, the 
form of the writ is either in the debet and detinet, that is, it states that 
the defendant owes and unjustly detains the debt or thing in question, it is 
so brought between the original contracting parties; or, it is in the 
detinet only; that is, that the defendant unjustly detains from the 
plaintiff the debt or thing for which the action is brought; this is the 
form in in action by an executor, because the debt or duty is not due to 
him, but it is unjustly detained from him. 1 Saund. 1. 
     2. There is one case in which the writ must be in the detinet between 
the contracting parties. This is when the action is instituted for the 
recovery of goods, as a horse, a ship, and the like, the writ must be in the 
detinet, for it cannot be said a man owes another a horse, or a ship, but 
only that he detains them from him. 3 Bl. Com. 153, 4; 11 Vin. Ab. 32 1; 
Bac. Ab. Debt, F; 1 Lilly's Reg. 543; Dane's Ab. h.t.