Hello and thank you for your question!
In terms of your question, do you mean that the pharmacist is actually withholding your prescription after you turned it in? I just want to be sure I understand the question.
Just for the sake of answering your question now, I am going to assume that a pharmacist is not returning an Rx to you after you turned it in. If this is not the case, please let us know and we can revise our answer for you!
So, the answer is a somewhat complicated one. There are no specific statements in the law stating a pharmacist can or cannot withhold a prescription. It usually up to what is called "professional judgment".
Different states word the laws differently, but here is New York for example:
"80.76 Dispensing; prohibition. Controlled substances shall not be prescribed for, administered or dispensed to addicts or habitual users of controlled substances except as provided by the Public Health Law or this Part."
"80.71 Practitioners, in good faith and in the course of their professional practice only, and as limited in this Part may dispense controlled substances."
So the words "good faith" comes up a lot. A Pharmacist has a LEGAL obligation to prevent abuse, illegitamte scripts etc. This obviously is extremely broad but usually the pharmacist can take measures to verify prescriptions by either calling the prescribing physicians or using other resources. Typically, most pharmacist wil not actually TAKE a prescription unless the prescriber says to actually destroy it. Most commonly, they will just refuse to fill it. It is certainly within their legal rights to refuse filling a prescription for various reasons. They should not however, just take a prescription and not return without good reason.
If your question is referring to holding onto the prescription AFTER it has been filled, then yes, the pharmacy must hold onto the prescription for legal purposes and record keeping. Typically you can get a copy printed out though.
If I interpreted your question incorrectly, please let me know and I will answer appropriately.