Reasonable

An innocuous-looking adjective that nonetheless exercises the wits of attorneys the world over, especially when modified by the word "commercially".

As long ago as 1947 Lord Greene MR issued the seminal words on the topic in the famous case of AP Picture Houses v Wednesbury: It must be proved to be unreasonable in the sense that the court considers it to be a decision that no reasonable body could have come to.

It also illustrates that even the Master of the Rolls can end a sentence with a preposition.

See

• AP Picture Houses v Wednesbury (includes link to transcript)
• commercially reasonable manner
• Barclays v Unicredit