Now known as a freezing injunction, a pre-trial court order preventing the disposal by a party of assets forming part of the subject matter of a case pending trial.
As Sir Robert Megarry V-C explained in Barclay-Johnson v Yuill  1 WLR 1259 at 1262:
“The Mareva jurisdiction takes its name from Mareva Compania Naviera S.A. v. International Bulk-carriers S.A.  2 Lloyd’s Rep. 509, a case which concerned the vessel Mareva: I shall call it ‘the Mareva case.’ Its immediate precursor was Nippon Yusen Kaisha v. Karageorgis  1 W.L.R. 1093. Both are decisions of the Court of Appeal on ex parte applications, and in both cases injunctions of the type now sought before me were granted against foreign defendants who had assets within the jurisdiction. I think that it is the Mareva case which has given its name to the injunction because in the earlier case the court had not been referred to Lister & Co. v. Stubbs (1890) 45 Ch.D. 1 or any of the other cases in that line which pointed in the opposite direction, and it was in the Mareva case that the Court of Appeal held that notwithstanding those authorities, the injunction should be granted.”