I suggest you read the Constitution. Amendments 9 and 10 say:
9: "The
enumeration in the Constitution, of certain rights, shall not be construed to deny or disparage others retained by the people."
10: "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."
Okay, so now we need to look at what powers the federal government has, and the limitations on states:
"Section 8 - Powers of Congress
The Congress shall have Power To lay and collect Taxes, Duties,
Imposts and
Excises, to pay the Debts and provide for the common Defence and general
Welfare of the United States; but all Duties,
Imposts and
Excises shall be uniform throughout the United States;
To borrow money on the credit of the United States;
To regulate Commerce with foreign Nations, and among the several States, and with the Indian Tribes;
To establish an uniform Rule of Naturalization, and uniform Laws on the subject of Bankruptcies throughout the United States;
To coin Money, regulate the Value thereof, and of foreign Coin, and fix the Standard of Weights and Measures;
To provide for the Punishment of counterfeiting the Securities and current Coin of the United States;
To establish Post Offices and
Post Roads;
To promote the Progress of Science and useful Arts, by securing for limited Times to Authors and Inventors the exclusive Right to their respective Writings and Discoveries;
To constitute Tribunals inferior to the supreme Court;
To define and punish Piracies and Felonies committed on the high Seas, and Offenses against the Law of Nations;
To declare War, grant
Letters of Marque and
Reprisal, and make Rules concerning Captures on Land and Water;
To raise and support Armies, but no Appropriation of Money to that Use shall be for a longer Term than two Years;
To provide and maintain a Navy;
To make Rules for the Government and Regulation of the land and naval Forces;
To provide for calling forth the Militia to execute the Laws of the Union, suppress Insurrections and repel Invasions;
To provide for organizing, arming, and disciplining the Militia, and for governing such Part of them as may be employed in the Service of the United States, reserving to the States respectively, the Appointment of the Officers, and the Authority of training the Militia according to the discipline prescribed by Congress;
To exercise exclusive Legislation in all Cases whatsoever, over such District (not exceeding ten Miles square) as may, by Cession of particular States, and the acceptance of Congress, become the Seat of the Government of the United States, and to exercise like Authority over all Places purchased by the Consent of the Legislature of the State in which the Same shall be, for the Erection of Forts, Magazines, Arsenals, dock-Yards, and other needful Buildings; And
To make all Laws which shall be necessary and proper for carrying into Execution the foregoing Powers, and all other Powers vested by this Constitution in the Government of the United States, or in any Department or Officer thereof.
Section 9 - Limits on Congress
The Migration or Importation of such Persons as any of the States now existing shall think proper to admit, shall not be prohibited by the Congress prior to the Year one thousand eight hundred and eight, but a tax or duty may be imposed on such Importation, not exceeding ten dollars for each Person.
The privilege of the Writ of
Habeas Corpus shall not be suspended, unless when in Cases of Rebellion or Invasion the public Safety may require it.
No Bill of
Attainder or
ex post facto Law shall be passed.
(No capitation, or other direct, Tax shall be laid, unless in Proportion to the Census or Enumeration herein before directed to be taken.) (Section in parentheses clarified by the 16th Amendment.)
No Tax or Duty shall be laid on Articles exported from any State.
No Preference shall be given by any Regulation of Commerce or Revenue to the Ports of one State over those of another: nor shall Vessels bound to, or from, one State, be obliged to enter, clear, or pay Duties in another.
No Money shall be drawn from the Treasury, but in Consequence of Appropriations made by Law; and a regular Statement and Account of the Receipts and Expenditures of all public Money shall be published from time to time.
No
Title of Nobility shall be granted by the United States: And no Person holding any Office of Profit or Trust under them, shall, without the Consent of the Congress, accept of any present,
Emolument, Office, or Title, of any kind whatever, from any King, Prince or foreign State.
Section 10 - Powers prohibited of States
No State shall enter into any Treaty, Alliance, or Confederation; grant
Letters of Marque and
Reprisal; coin Money; emit
Bills of Credit; make any Thing but gold and silver Coin a Tender in Payment of Debts; pass any Bill of
Attainder,
ex post facto Law, or Law impairing the Obligation of Contracts, or grant any
Title of Nobility."
So, to sum up, the feds may exercise those powers specifically given to them, and anything else is reserved to the states. The feds actually have very limited powers. The feds can't simply do whatever they want.