Law:
Under Section 7(6) if the Road Traffic Act 1988 it is an offence for a person who has been required to provide a specimen for analysis to fail without reasonable excuse to do so. If this is in relation to driving or attempting to drive there is a mandatory disqualification. If only “in charge” there is a 10 penalty point endorsement with discretionary disqualification. Aggravated offences can lead to custodial sentences.
It is a defence if you can show that you had a reasonable excuse for not providing a specimen