What is required by states or not is irrelevant if you signed a contract.
If the contract says "I will give two weeks notice before I leave" and you sign on the dotted line, then you need to give two weeks notice before you leave or else suffer the penalties described in the contract.
You can't cite laws to get out of contractual obligations unless the contract demands you do something illegal.
> What is required by states or not is irrelevant if you signed a contract.
Employers cannot get out of legal requirements just by having employees sign contracts. Not all rights can be waived.
> If the contract says "I will give two weeks notice before I leave" and you sign on the dotted line, then you need to give two weeks notice before you leave or else suffer the penalties described in the contract.
Well, it would have to be a valid contract, and the penalties described in the contract would have to be legal (you can't put punitive damages in a contract). If, some time after you are hired, the employer asks you to sign a contract that says that you will give two weeks notice, and you sign on the dotted line, that's not actually a valid contract (because there's no consideration).
> You can't cite laws to get out of contractual obligations unless the contract demands you do something illegal.
In general you can breach any contract, there are many laws which give reasons why a contract would be void, or laws which prevent employers from entering into certain types of contracts, and reasons why a contract would not be enforced or possibly unenforceable.
If the contract says "I will give two weeks notice before I leave" and you sign on the dotted line, then you need to give two weeks notice before you leave or else suffer the penalties described in the contract.
You can't cite laws to get out of contractual obligations unless the contract demands you do something illegal.