The drugs screening does not specify nor the company ?
If your employer is a public entity (for example, a municipality) or is doing drug testing under a government program (like a drug-free workplace program), then you may have constitutional rights at stake. Whether they're violated will depend on the type of job (was it safety-sensitive?) and the reason for test you (was it random or suspicion-based?). It would be best to speak to an attorney familiar with these issues. If you have a valid case, a federal statute allows you to recover attorney's fees from the defendant. That enables a lawyer to take such a case on a contingent basis.