It is not quite as simple as it appears to be an effective manager in that there is much more to being a successful manager than just creating an environment that is protected by labor laws and creating relationships. Managers are charged with so many tasks those particular tasks are just a small part. As you pointed out, employees have too much information it is incumbent upon leadership to know, understand and interpret the laws that apply to the workplace environment.
There are many torts, to be aware of as well. Torts are laws that offer remedies to individuals that have been harmed by the unreasonable actions of other people. When there is a discussion on tort claims, typically they involved state law. There are two types of torts, intentional and negligent. Intentional torts are usually offenses committed by an individual that intended to do harm. Negligent torts are committed without intent or expectation to do harm.
How will this knowledge improve and protect the workplace environment?