It doesn't matter where the offence was committed to the CBP. The fact you committed one does.

There are recent reports that Canadian nationals seeking entry to the US are being denied entry when admitting to marijuana usage in places where its use is lawful. If that is the case, it follows that CBP would deny GE on the same basis.

Re-reading the basis of denial, it is not merely that the applicant has violated US law, but that his use of marijuana in general is a reason to deny GE.

If all of your usage is in a place where it is not a violation of any law, then go ahead and try an "appeal" to the Ombudsman. Make it clear when and where the usage occurred and that the usage was not in violation of any law at the time it occurred.

I strongly suspect that this will do you no good, but it is worth the effort to see what comes of it. Additionally, should US policy change at some point soon, you will have made a record to be reconsidered.

As others note, if you cannot make this specific case it is not worth the bandwidth or postage to submit.

Is there a "do you use drugs" question on the GE application then? I only remember a question that went along the lines of "have you been convicted of any criminal offense in the US or any other country?". I cannot think why any sane person would admit to "usage" if there had not been a criminal conviction associated with it and was therefore worried about checks that may be made in other countries. Anyway, I will be amazed if they have any luck.

You'd have to be barking mad to admit to it in a "lifestyle" type of question at any stage of the process if there was no associated offence in any country.

Back on planet earth, if a CBP person asks me if I have ever smoked marijuana (I haven't so it is a moot point) the answer would be "no". Why not ask "did you ever steal from the church plate?", or "did you ever steal someone's newspaper?", or "did you ever hit someone's car and drive off?", and so on. The answer to all of them would be no and if they find out otherwise then good luck to them. But my lifestyle and what I do in my private time is nothing to do with them so I will not give them the information for them to make a judgement as it could go either way.

They may think that little green men live on Mars, but I won't help them prove it.

I'm sure you get the point. If not, don't worry.

Advising people to commit a felony, e.g. making a false statement to a CBP Officer, is a bit silly. While there are certainly people who do and can justify it to themselves, making the recommendation without accompanying it with the risks is poor form.

Will anybody likely be prosecuted for this casual lie? Not likely. But, if it happens, one would likely wish to have at least considered it.

If you're referring to me I didn't advise anyone to lie. I said what I would do, and what I think of people that would answer a question such as that if they had not been convicted of an offense.