The CFTA: Tobacco Carveouts are Spreading

Carveouts for tobacco control measures are spreading. The carveout was first used in the TPP, then was brought over to the Australia-Singapore FTA update. Now there is one in the Canadian Free Trade Agreement:

Article 806: Tobacco Control Measures

This Agreement does not apply to any measure adopted or maintained by a Party relating to tobacco control.

But why is this needed?  When is there a risk that a tobacco control measure will violate a trade agreement?  And if there is such a risk, by carving out tobacco control measures but not other public health measures, aren't you ignoring the broader issue?