Market overt or marché ouvert (Law French for "open market") is an English legal concept originating in medieval times governing subsequent ownership of stolen goods.

[2] In general, the sale of stolen goods does not convey effective title (see Nemo dat quod non habet).

However, under marché ouvert, if goods were openly sold in designated markets between sunrise and sunset, provenance could not be questioned, and effective title of ownership was obtained.

[9][10] Estelle Morris, Minister for the Arts stated during the second reading of the Dealing in Cultural Objects (Offences) Bill in July 2003:I did not have information about marché ouvert in the deep recesses of my mind, but experts reliably inform me that it no longer exists.

Believe it or not, in this land of ours, people could sell stolen—my officials put "dodgy" in brackets, but we do not use that term—objects.