On 9 December 1986 the Federal Court of Justice decided the Honda case. The plaintiffs’ son had been riding a Honda Gold Wing motorcycle on the autobahn from Nuremberg to Munich at 140 to 150 kilometers per hour. He died at the scene of the crash. The cause was a handlebar fairing made by another firm and fitted after the sale. At high speed it reduced the grip of the front wheel.
The court set out the Produktbeobachtungspflicht, the duty to observe the product. A manufacturer must keep itself informed about the consequences of how its product is used. The duty also covers accessories made by other firms, when they are necessary, intended or in common use.