In British and British-derived legal systems, an Anton Piller order (frequently misspelt as Anton Pillar order) is a court order which provides for the right to search premises without prior warning. This is used in order to prevent the destruction of incriminating evidence, particularly in cases of alleged copyright infringement.

The first such order was issued in the case of Anton Piller KG vs Manufacturing Processes Limited in 1976. Because such an order is essentially unfair to the accused party, Anton Piller orders are only issued exceptionally, when

1. There is an extremely strong prima facie case against the respondent,
2. The damage, potential or actual, must be very serious for the applicant, and
3. There must be clear evidence that the respondents have in their possession incriminating documents or things and that there is a real possibility that they may destroy such material before an inter partes application can be made.

Quotations

"Let me say at once that no court in this land has any power to issue a search warrant to enter a man's house so as to see if there are papers or documents there which are of an incriminating nature, whether libels or infringements of copyright or anything else of the kind. No constable or bailiff can knock at the door and demand entry so as to inspect papers or documents. The householder can shut the door in his face and say, 'Get out.' That was established in the leading case of Entick v. Carrington (1765), 19 State Tr. 1029. None of us would wish to whittle down that principle in the slightest. But the order sought in this case is not a search warrant. It does not authorise the plaintiff's solicitors or anyone else to enter the defendants' premises against their will. It does not authorise the breaking down of any doors, nor the slipping in by a back door, nor getting in by an open door or window ... The plaintiffs must get the defendants' permission. But it does do this: It brings pressure on the defendants to give permission. It does more. It actually orders them to give permission – with, I suppose, the result that if they do not give permission, they are guilty of contempt of court." -- Lord Denning