The mandatory use of bycatch reduction devices (BRDs) in prawn trawl fisheries is now commonplace in Australia. BRDs are designed to allow unwanted or juvenile species to escape fishing nets with consequent benefits for the abundance of such species, species which prey on them, and general ecosystem integrity. In the Queensland East Coast Trawl Fishery, as well as in a handful of other Australian prawn trawl fisheries, specific turtle excluder devices (TEDs) are required to prevent turtles from entering the codend section of trawl nets. This article reviews international and Australian legal measures to protect turtles from prawn trawl fishing activities. It focuses on the difficult task fisheries officers in Queensland were presented with in 2002 when they attempted to prosecute two fishers for alleged non-compliance with their licence requirement to use a device which enables turtles to escape “immediately” after being taken in the net. A review is presented of this case which highlights the difficult task of securing convictions for alleged non-compliance with fisheries regulations where scientific uncertainty compounds the establishment of the required evidentiary burden of proof. The decision in the case exposes the challenge drafters of legislation face when they attempt to translate sound fisheries management objectives into effective and enforceable law.