What if violent crimes left an imprint on a murderer’s soul? What if it were possible to pursue a suspect by literally following in their shadow? What if you could use remote viewing (clairvoyance) or hearing (clairaudience) to conduct surveillance? What if divination could tell you who pulled the trigger of a gun?

Some of the problems in using magic for law enforcement is that the magic doesn’t necessarily follow rules that can be easily understood, and thereby break suspension of disbelief. If anyone has access to magic, why doesn’t everyone use it? If criminals know magic can be used to catch them, why don’t they use it to hide their crimes?

One solution is to limit the use of magic to individuals, making it less available, and more special. Another solution is to give magic certain rules that it must follow, like physics or something. These fall apart if you don’t follow your rules, so it helps to understand what you’re trying to accomplish and why it works the way it does.

Then, there are also questions of the legality of using magic to catch criminals. Presumably, the same techniques used to determine someone’s guilt can be used to incriminate them. This problem exists in our current society. How do you conduct a magical investigation ethically? How do you guarantee fairness for anyone?

You have the “stick” to fall back on, I suppose. “We have the stick, and we promise never to use unless we have to — now everyone behave.” It really is a problem when things become so complicated your average person can’t tell how the rules work, or why one person is guilty of X when someone else is guilty of Y.

…And of course there’s the problem of consistency. How do you guarantee anyone’s safety when there are people still committing crimes and getting away with them? How do you enforce the rules for everyone? It becomes more and more difficult the larger the area, and the more things are made illegal. It becomes more complicated.

Even when you have magic.

What do you do? Create magical constructs to help ensure the rules are enforced? Make nothing illegal? Maybe, creating some kind of honor system, where the citizens themselves enforce the rules, inasmuch as they are able. Responsibility might be transferable be individuals sharing a special connection, like blood relatives.

Certainly some things worth consideration.