There are so many things that the federal government can do in these confused times. They can prevent you the use of your personal property without recompense. They can fine you if you wash your car in your driveway and the runoff goes into a roadside wash that has been there to carry off rainwater for decades. They can track your movements. If you are a dairy farmer they can not only prevent you from selling your raw milk to your neighbors, they can prevent you from drinking it yourself. They can also prevent you from growing your own corn to feed your cows.
The government can tell your state what they must teach in your schools. That is why so many things are taught against a parents better judgement and so many things are overlooked like American History. They can tell your state how many prisoners they may keep in your jails and how your highways must be paved. The powers of the federal government are virtually limitless. They shouldn't be. They weren't intended to be. But they are. It has been an ugly evolutionary process that has worked because no one (representatives and senators) would draw the line. That is because as federal power grew, the power of the congress grew along with it. And, God, how those people love power.
In theory the federal government has only the power it is given in the Constitution. That is very limited. So how did this overwhelming power come about? In, oh so many, ways. One way is the power of the pen. That would be the pen that signs those big federal checks. The checks that help pay for schools. Or the checks that rebuild roads or build a new post office. I believe that I have heard somewhere that money talks etc.
But there are other ways also. The United States Constitution is not a detailed instruction manual on how to run a country. It is a glorious framework upon which a great nation can be built. That is both it's strength and it's weakness. The weakness being that the words of the Constitution lend themselves to various interpretations. The Federalist Papers help us to understand what the founders were thinking. But they do not have the power of law, so the executive branch gets to make their own interpretations. As long as these interpretations are not questioned, they stand. If they are questioned various courts get involved. In ultimate extremes, the Supreme Court makes the final decision.
So what and where are these words that provide cover for government over reach? If you look at the preamble to the Constitution you see the phrase "promote the general welfare". What promotes the general welfare? Some would say the TSA promotes the general welfare although it is not an assigned right under the Constitution. I'm sure many would argue that the TSA hinders the general welfare. Unless it goes to the courts, the administration wins the issue.
Article one, section eight, of the Constitution boasts a couple of catch-all phrases that are handy tools for those wishing to expand federal reach. The first is "to provide for the common defense and the general welfare". That "general welfare" thing gives a lot of wiggle room if you are big on government control. There is a phrase, "to regulate commerce with foreign nations and among the several states". There is lots of room to take control there. Almost everything is shipped across state lines at some time. That's when the feds get their nose in the tent. Finally, we have 'to promote the progress of science and useful arts etc". That phrase allows for patents and copyrights. The length of those protections is in control of the federal government. That is a make or break power for business.
The Tenth Amendment says that the powers not expressly given to the federal government comes to the states and the people. But historically, if the feds want it they get it. That is exactly why we need a much smaller government. That big dog in Washington needs lots of bones. And when they get them they abuse them. The best government is that government closest to the people. Never forget, States have rights too.