What are 3 laws that congress can pass and 3 laws that they do not have the power to pass?

Answer 1

Congress has the power to pass:

1. Any Immigration laws it chooses, as long as it doesn't violate the Bill of Rights. This, like almost all constitutionally allowed Congressional powers, is given by article 1, section 8: "To establish an uniform Rule of Naturalization, and uniform Laws on the subject of Bankruptcies throughout the United States"
2. Laws regulating ACTUAL interstate or international commerce, for example forbidding (or establishing, if they were foolish enough) tariffs between states. Were Congress to actually bother addressing the regulations that effectively make multistate insurance companies illegal, for example, that would be constitutional, and good. So of course they do not. All of this is covered by article 1, section 8: "To regulate Commerce with foreign Nations, and among the several States"
3. Any laws changing the way coins/money is made, or its value, is constitutional, because that is explicitly mentioned in article 1, section 8: "To coin Money, regulate the Value thereof, and of foreign Coin, and fix the Standard of Weights and Measures"

Congress has already passed many laws it has no legitimate power to impose, because of the 9th and 10th amendments. Examples of this include:

1. The drug prohibition. The reason an amendment was passed to ban alcohol is that it was understood Congress could never pass it legitimately, otherwise. Likewise, it has no power to prohibit any other recreational drug or activity.
2. Any law regulating consensual activity like trade that is not actually "interstate commerce", for example toilet tank size, lights, and so on. The idea that all trade is magically "interstate commerce", even when it is actually just commerce on an indeterminate level is not actually intended by the authors to be covered under that "clause". Oh, and this includes even more absurdity like the FBI being able to take over local law enforcement's role for kidnapping "because it might have crossed state lines".
3. All laws imposing regulations on the various states, which are not identified ahead of time as powers in the Constitution, like the Department of Education. It is clear that the intent of the Founders with the 10th amendment was NOT for it to be bypassed by any future laws levying taxes and then doling out the money as a reward to any state that complied.

Those are forbidden by the Bill of Rights amendments:

Amendment IX

The enumeration in the Constitution, of certain rights, shall not be construed to deny or disparage others retained by the people.

Amendment X

The powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved to the States respectively, or to the people.