Originally in Scotland, imprisonment for debt was enforceable only in certain cases, but a custom gradually grew up of taking the debtor's oath to pay.
If the debtor broke his oath, he became liable to the discipline of the Church.
The civil power could step in to aid the ecclesiastical, denouncing the debtor as an outlaw, imprisoning his person and confiscating his goods.
The subsequent process, a warrant directing a messenger-at-arms to charge the debtor to pay or perform in terms of the letters, was called letters of horning.
This system of execution was simplified by the Debtors (Scotland) Act 1838 (1 & 2 Vict.