Piggott v DPP [2008] All ER (D) 114 (Feb)
For the purposes of s 7 of the Road Traffic Act 1988 (requirement to provide a specimen of breath for analysis) there is no legal obligation on the individual to declare a medical condition which might make it difficult or impossible for him to provide the specimen.
However, a failure to communicate that excuse at the time when the specimen is sought is highly relevant in deciding whether or not such a belated excuse was a reasonable one.