I've read in an Austrian initiative a few months ago that it could help to distinguish between the metabolites 11-OH-THC and the resulting 11-COOH-THC since the latter one isn't psychoactive and is formed only about 19h after the last intake if I remember correctly, so this could help with finding proper regulations:

https://en.wikipedia.org/wiki/11-nor-9-Carboxy-THC

This topic is definitely one of the biggest issues holding back the legalisation/decriminalization in many countries in my opinion, it's great that finally there's some research done regarding this.