The law says "unless you've explicitly agreed otherwise, you can end an employment relationship with no conditions". This person explicitly agreed otherwise, then reneged on their agreement, that's a breach of contract.

If both provisions were in the contract, then what you're stating would suggest that the company could not refuse to pay for the unused vacation time, either. But, again, that doesn't appear to be the case here.

For completeness's sake, there are 38 states with an "implied contract exception" to at-will employment, where statements in the employee handbook would count as implied contract and be binding, but Florida is not one of them.

The statements in an employee handbook can be binding on the employer, but never the employee. This is well-settled case law in the US. (Whether it is actually binding depends on the specific language used, so I edited my comment from "is" to "can be".)

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.

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.

So, yes, you can cite laws.

That is simply untrue. There are a number of reasons a contract can be deemed invalid or unenforceable. Illegality is only one such reason.

This is so completely wrong that it's almost exactly the opposite of the truth. Two weeks notice is a courtesy except for term-defined employment contracts where the length of employment is an explicit, defined term of finite duration.