Originally Posted by
reclusive46
It's also worth noting, that while some terminal configurations in some Canadian airports, do allow you to bypass and go straight back to US customs, its actually a breach of the Canadian customs act to do so (As you must report to a CBSA officer).
That by pass when available and open is staffed by a CBSA officer who check your travel documents and BP.
It is available at YYZ T1 but not T3