I'm the Canadian who was detained by ICE for two weeks

Apparently she broke several rules and it’s bordering on fraud.

- She worked in LA on a TN that was revoked

- She applied for a TN visa at the Canadian border and was denied

- She then flew to Mexico to try again at the San Diego border (USCBP can see this and explicitly say not to “crossing shop”)

- Her new TN was sponsored by a company she owns for another drinks company she also owns (you can’t self-sponsor a TN visa)

- The company she was consulting for was making THC drinks which are still illegal under USA federal law

My guess is she was questioned and determined to be committing immigration fraud and was detained until she could be deported

So deny her entry and let her airline deal with returning her? Why did she need to be imprisoned? International Law says that if you're denied entry the onus is on your flight carrier to return you, which is a private matter between you and the carrier.

She crossed the land border - there is no airline.

Ah, even easier then, just tell her to turn around.