My point of view is irrelevant?
What you call over reaching is irrelevant to the question of whether they are acting legally. I think it's over reaching for the government to prohibit marijuana use. But my thoughts on the matter don't change the fact that it's a constitutional law.
Are you contending that every action taken by the EPA, USDoE, etc. originates as a law passed by congress and signed by the President? I.e., new greenhouse gas regulations....
It is not necessary for every action to originate in Congress and be signed by the President. The Congress need only grant authorization to act. To use the EPA as an example, it was created by executive order to enforce environmental laws. One of those laws, passed by Congress, is the Clean Air Act, which requires the EPA to develop and enforce regulations regarding greenhouse gases, among other things. This power has been upheld by the Supreme Court as constitutional, with the court actually going beyond the question of "power" and pointing out the fact that under federal law the EPA is
required to develop and enforce such regulations.