Stormcloud said "Interesting comments here. How about this one. "It's a law that you get a wiring permit." These comments are suggesting that it's ok to break the law. Hmmm. "
Electrical code is not "law". There is no electrical police who will be laying charges.
However, the authorities who inspect and enforce code adherence could intervene in serious ways to correct dangerous situations. The prime purpose of the Canadian Electrical Code is to prevent fires. This is in the preamble since 1921, roughly, when the first code was written.
Nobody wants to burn their property down, and non adherence to code could void property insurance, those are possibly more serious penalties than any law.
As said, if having to ask simple questions on a public forum, the signs are strong that this is a job not to touch. Free spaces in a panel are a good thing, extra capacity should always be available. Free spaces should have the plastic snap in covers installed.