Rules of origin

From my point of view, it is pretty effective. Goods must be accompanied by a "Certificate of Origin" to qualify for any free trade agreement. This document will be reviewed at some point. It should be noted that at the time of release, goods are not thoroughly examined or checked. Less than 1% of all goods are actually examined. Documents alone are used to release goods.

Post-audits, on the other hand, are quite common. You may be asked to provide additional proof of origin later on. Customs in Canada has the authority to audit an entry up to four years after the goods have arrived.

Customs officials also have a lot of experience and a lot of data in their computers that they can quickly check. They know who makes what and how to spot a suspicious shipment.

I really like this article because it can help clarify things from a legal perspective as well: EXIMA’s Library | What You Need to Know About the Rules of Origin