When magic exists, there are obviously going to be people or creatures in your world who will try and utilize that magic somehow. There are often two main ways this is dealt with: through wielding objects that have innate magical power, or the person themselves having some sort of innate magical ability.
Even in a world where everyone has the ability to do magic it may not be a good idea for everyone to actually do magic. This will intertwine with laws for magic use a bit, but qualifications are a little different. While laws may govern the use of magic, especially in public arenas, qualifications are more about who is capable of doing magic.