This question applies mainly to consumer products such as food (including health and supplemental), clothing, pharmaceuticals, cosmetics etc. The major enforcers of these laws are the Canadian Border Services Agency (CBSA - http://www.cbsa-asfc.gc.ca/), the Canadian Food Inspection Agency (CFIA - http://www.inspection.gc.ca/), Health Canada (http://www.hc-sc.gc.ca/), and Industry Canada (http://www.strategis.ic.gc.ca/).