PAAB review is not required by law. The PAAB Code is a voluntary code supported by the major pharmaceutical industry trade associations and endorsed by Health Canada which has ultimate legal authority for drug advertising in Canada. If companies choose not to come to the PAAB and the PAAB receives complaints about their advertising or we find code infractions through our monitoring activities, the PAAB will ask Health Canada to intervene. The PAAB endeavours to make the unique Canadian healthcare product advertising self-regulation system work for all companies in the best interest of Canadian patients.
Note that, for some pharmaceutical trade associations, PAAB preclearance of advertising is a condition of membership.
Also note that Health Canada is currently considering requiring preclearance of opioid advertising and Risk Management Tools. https://www.canada.ca/en/health-canada/news/2018/06/minister-of-health-ginette-petitpas-taylor-announces-intent-to-severely-restrict-marketing-of-opioids.html