Can we send applicants to a drug screening before a job offer is made?

Q: “The company has been sending people at the time of their job application to a drug screening. There has been no conditional job offer extended. They may send four people for the same job and then hire one of them, assuming every one of them passed the screening. I am telling them that this is illegal, and that we need to have made a conditional job offer or else we are asking for medical information from people who have no employment connection to us. Are we breaking the law?” – Kary, Florida