Generally, under federal law, an employer cannot withhold a final paycheck. Federal law, i.e., the Fair Labor Standards Act ("FLSA"), requires that an employee be paid a minimum wage. When the employer fails to pay any paycheck at all, the employer has failed to pay a wage for the final pay period. Failure to pay any wage at all means that the employer has failed to pay the minimum wage required by federal law. That is the basis for many minimum wage lawsuits. If the overtime wage provisions of the FLSA are implicated, then the employee might also be able to sue for minimum wages.
Under state laws, such as Florida law, an employee could also sue to recover his or her final paycheck for breach of contract.
Below is a link to the U.S. Department of Labor website, containing information on the federal minimum wage requirements under the FLSA.