s103 Corruption and bribery of member of Parliament (1) ... (2) Every one is liable to imprisonment for a term not exceeding 7 years who corruptly gives or offers or agrees to give any bribe to any person with intent to influence any member of Parliament in respect of any act or omission by him in his capacity as a member of Parliament. (3) ...
"Bribe" is defined in section 99 as:
Bribe means any money, valuable consideration, office, or employment, or any benefit, whether direct or indirect:
I haven't got time to develop the argument but:
- There's a difference between concluding that such offers are politically objectionable (controls might be transparency and ultimately voter response at the ballot box) and that such offers triggers criminal liability.
- Interestingly, the home of the origins Westminister system, the UK, does not have the same criminal liability.
- There's a need to reconcile the offer with offers from groups like, say, an anti-alcohol lobby groups who might say to a party, "we'll make a donation to your party if you support raising the drinking age; but if you don't, we won't".
- There's a wee bit of literature and jurisprudence on the issue but I haven't got time to go through it. Two goods reads though:
> AG of Ceylon v de Livera (a case under a similar section) > Zellick, "Bribery of Members of Parliament and the Criminal Law"  Public Law 31 (on the UK situation, remembering there is no specific offence)