Hi Jimmy --
Drug testing is done for a lot of different types of reasons. Has your Company just now implemented a drug-free workplace policy? If the policy has always been in place, how was it administered before? Do you have a written policy on drug testing? When do you drug test? Upon hire? Reasonable suspicion? Accidents? Random? Some or all of those? Others?
Here is a blurb from http://www.uschamber.com/sb/business/P98/P98_05_1075_FL.asp
Florida's drug-testing law is contained within its workers' compensation law — a law covering employers of four or more, except in the construction industry where the law covers employers of one or more. Under the law employers may voluntarily implement drug-free workplace programs designed to lessen the frequency and severity of work-related injuries. If an employer implements a drug-free workplace program that includes notice, education and testing for drugs and alcohol following the rules for testing developed by the Workers' Compensation Division, the employer may require that an employee submit to a test for the presence of drugs or alcohol and, if a drug or alcohol is found to be present in the employee's system at (or above) a level prescribed by law, the employee may be terminated and forfeits eligibility for medical and indemnity benefits. In addition, the employer is eligible for reduced workers' compensation rates.
To qualify for reduced rates, an employer's policy must provide for testing of all job applicants, reasonable suspicion drug tests, and follow-up-tests for those participating in employee assistance programs unless the employee voluntarily entered the program. It may also provide for routine fitness-for-duty medical exams, including drug testing. A private employer may conduct random testing, or any other lawful testing, of employees for drugs.
As with many fairness oriented things, your feelings about a person's drug use is probably irrelevent. At the minimum, you must follow what your policy states. If you don't have a policy, you need to get one put together that complies with Florida law. Whatever is meant by "notification" and "education" would be critical points. You will also want to find out about what to do in the event of a person found to have a legal amount of a legally prescribed drug that may impair them and, because of their job duties, create a safety hazard.
I agree with the other two posters that consistency is the key here. You need to create a policy. If you are going to test pre-employment then you need to test for all candidates (not knowing FL law, you need to find out whether you can test pre-offer or post-offer). Also you need to decide if you are going to do random tests and reasonable suspicion tests (alcohol, drug or both). I have worked for a company that did pre-employment tests, did not do random tests, but did do reasonable suspicion tests. For reasonable suspicion I recommend that prior to having someone take a test that you have two managers observe the individual so that you have two witnesses for why there was reasonable suspicion. Look for a local company that does employment tests (in the past we used a local place that does pre-employment drug tests, reasonable suspicion and random drug and alcohol tests, DOT physicals and was also our workers comp facility). If you use many of their services they are likely to cut you a break on the costs.
It is mandatory that you follow your company policy (if it is legal) with all employees. You can't say "this guy looks ok" or "this one needs to be tested". If you make a exception for one and then don't hire the next one b/c he did not pass you're asking for a law suit. They can and will come up with any number of reasons you decided to drug test them and then didn't hire them...Example their race, gender, age, religion...
I currently work on a construction site with more than 800 employees including sibs. Our policy is that all of our employees, including managment, has an observed drug screen before entering on site. We require the same of our sub contractors. You would be surprised at whom you think are clean when they really are not. There are so many new items out there for users to fake their urine. Common things like visine and items sold at helath food stores and GNC. It is best to observe all employees to keep legal action from being brought againt you or your company.