It is indeed good advice to mug up on ARB rules, as Sean O'Mahony states (AJ 14.9.00), and it is the case that the ARB code requires that architects inform their client at the time of appointment that they are subject to the disciplinary sanction of the ARB.
The RIBA code of conduct also requires that RIBA members inform clients at the same time about their professional indemnity insurance, to avoid the problem of insurers not wishing to inform clients about their professional indemnity insurance when a claim is being made against them.
However, failure to comply with either the ARB or the RIBA codes does not leave an architect open to prosecution. The ARB uses disciplinary sanctions in relation to breaches of the code. The Architects Ac t a l lows the ARB to use prosecution only for the purpose of dealing with misuse of the title 'architect' by non-registered persons.
What architects can and have been prosecuted for is not informing their clients about their obligations under the CDM Regulations at the time of appointment (or even earlier).
Tim Gough, Austin Winkley & Associates