Examines injunctions "contra mundum" and against unidentifiable defendants after "South Cambridgeshire DC v Persons unknown " ([2004 EWCA Civ 1280), the first time the jurisdiction to make injunctions under the Town and Country Planning Act 1990 s187B has been considered by the CA. Analyses the judgment and the injunction based on the wording of s187B of the Act, the accompanying court rules and two recent decisions "Bloomsbury Publishing Plc v News Group Ltd " ([2003] 1 WLR 1633) and "Hampshire Waste Services Ltd v Persons intending to trespass and/or trespassing upon incinerator sites" ([2003] EWHC 1738 (Ch)). Places the "contra mundum" power recognised in "Hampshire Waste" and "South Cambridgeshire" within the wider context of injunctions having effect against persons other than named defendants. Discusses practical issues concerning s187B injunctions that have emerged from the above cases.