You're being accused of a crime, driving while intoxicated. If they're investigating a crime, I expect my rights to be upheld, and they need probably cause.

Oh my friend I don't even know where to begin.

Probable cause does not exist in Canadian law. There is no such concept.

The Charter of Rights and Freedoms says:

8 -- Everyone has the right to be secure against unreasonable search or seizure.

Not every search is covered by section 8. It is essentially not a right against search and seizure, but a right to privacy. In particular, privacy from intrusion by the state into very intimate and personal matters that touch the very core of being human. Officers digging through your love letters, your business contracts being publicly discussed in the media as part of court record.

That is what Canadian law guarantees you as a right.

Unless you are arguing that your blood alcohol content while driving is something you have a reasonable expectancy of privacy to, the entire argument about unreasonable search collapses on itself.