For ministers, I'm not aware of a specific certification that they sign. Again, there's a difference between the position of ministers and GIC appointees. Those who are appointed by the Governor in Council have certain rights under contract law. A certification, and so on, is an important process point that you have to take if you want to make it clear that under the conditions of the contract of their appointment there is an obligation to follow these ethical standards and guidelines.
On November 17th, 2009. See this statement in context.