20.—(1) On the hearing of a charge for an offence under section 49 or 50 of the Principal Act, it shall not be necessary to show that the defendant had not consumed intoxicating liquor after the time when the offence is alleged to have been committed but before the taking or provision of a specimen under section 13, 14 or 15.

(2) Where, on the hearing of a charge for an offence under section 49 or 50 of the Principal Act, evidence is given by or on behalf of the defendant that, after the time when the offence is alleged to have been committed but before the taking or provision of a specimen under section 13, 14 or 15, he had consumed intoxicating liquor, the court shall disregard the evidence unless satisfied by or on behalf of the defendant—

(a) that, but for that consumption, the concentration of alcohol in the defendant’s blood (as specified in a certificate under section 19) would not have exceeded the concentration of alcohol for the time being standing specified in subsection (2) of the said section 49 or 50, as may be appropriate, whether generally or in respect of the class of person of which the defendant is a member,

(b) that, but for that consumption, the concentration of alcohol in the defendant’s urine (as specified in a certificate under section 19) would not have exceeded the concentration of alcohol for the time being standing specified in subsection (3) of the said section 49 or 50, as may be appropriate, whether generally or in respect of the class of person of which the defendant is a member, or

(c) that, but for that consumption, the concentration of alcohol in the defendant’s breath (as specified in a statement under section 17) would not have exceeded the concentration of alcohol for the time being standing specified in subsection (4) of the said section 49 or 50, as may be appropriate, whether generally or in respect of the class of person of which the defendant is a member.

(3) (a) A person shall not take or attempt to take any action (including consumption of alcohol but excluding a refusal or failure to provide a specimen of his breath or urine or to permit the taking of a specimen of his blood) with the intention of frustrating a prosecution under section 49 or 50 of the Principal Act.

(b) A person who contravenes this subsection shall be guilty of an offence and shall be liable on summary conviction to F21[a fine not exceeding €5,000] or to imprisonment for a term not exceeding 6 months or to both.

(4) Where, on the hearing of a charge for an offence under section 49 or 50 of the Principal Act, the court is satisfied that any action taken by the defendant (including consumption of alcohol but excluding a refusal or failure to provide a specimen of his breath or urine or to permit the taking of a specimen of his blood) was so taken with the intention of frustrating a prosecution under either of those sections, the court may find him guilty of an offence under subsection (3).