What is a good career involving rules or leadership if I want to have definite hours?

Agree with the comments above. Attorneys work irregular hours overall but it's more common in a law firm setting. In-house attorneys generally have more control over their hours but this isn't always the case.

Certain areas like compliance may be better for you. Those roles are available at many different kinds of companies, involve rules and regulations, enforcing them, making sure they're adhered to, and likely would not involve working around the clock.

But as you go up the corporate ladder into more leadership roles, working longer hours and irregular hours becomes more common.

Consider being a probation officer. It seems to be a fit to what you're describing.

There are some areas of law which would cater to definite hours and leadership, primarily in a corporate setting; however, most areas of law require long and irregular hours depending on your cases or assignments at any given moment.

Agree most law jobs you don't have definite hours. Especially a job where you litigate (fight it out in court). At least if you're a lawyer. Paralegals or legal assistants tend to have better hours.

Also, accounting also you won't always have definite hours. I worked for an accounting firm and the tax accountants have long, irregular hours when tax returns are due.

I don't work in these fields but you may want to ask the kinds of hours that people have in these fields:

computer programmer, IT manager and software developer

They all involve technology and you like that!

Also one thing you should understand that it is increasingly harder to find jobs where you only work a set number of hours, especially if you work in a field that requires a gradaute degree (master's degree, law degree, PhD).