The issue around Mountain Dew was actually a concern about marketting caffeine to kids (at the time) although there were other poorly enforced rules against it.
Here's the copy paste:
1. Caffeine is listed as a Miscelaneous additive in the Food and Drug Regulations, it is permitted only in "Cola-type beverages" at a maximum of 200 parts per million or 200 mg/L.
2. Producers of products other than cola which wish to include caffeine must submit a Food additive submission to Health Canada justifying their desire.
http://www.hc-sc.gc.ca/.../sub_prep_demande-eng.php
3. Schoolyard legends of caffeinated American Mountain Dew may come true in Canada. In March 2010, Health Canada authorized the immedate marketing of caffeinated non-cola type soft drinks after an industry submission requested the exemption. Non-cola carbonated drinks may be artificially caffeinated to 150 ppm.
http://gazette.gc.ca/...notice-avis-eng.html#d106
4. Sneaky sources of caffeine should be disclosed. From Health Canada:
" If an ingredient, that is a relatively unknown source of caffeine (e.g. guarana, yerba maté), is added to a food, the total caffeine content of that food should be indicated on the product label in milligrams (mg) of caffeine per stated serving size."
http://www.hc-sc.gc.ca/...age-caf-labelling-eng.php
5. Energy drinks are considered Natural Health Products in Canada and are not subject to the Food and Drug Regulations. They may contain added caffeine.