Here's the thing: When we simply prohibit our teenagers from dating, or anything else for that matter, we are missing a MAJOR opportunity to help them learn useful life skills while they are still receptive to our guidance and input. (Even though some adolescents don't seem receptive anymore, they are. It's just against the 'teen code of honor' for them to admit it!)
Protective action was very appropriate when your daughter was a young child. Now, too much protection of her as a teenager may actually backfire. How is she going to learn anything without the opportunity to gain experience?
In my freshman year of college, there was a girl down the hall who had been prohibited from dating in high school. Within her first week of dizzying freedom, she managed to become dangerously drunk, lose her virginity, and get kicked out of the dorm for violating curfew. All in one night! I'm betting her parents wish they had allowed a more gradual initiation to take place while she was still at home.
Please, let your daughter practice dating while she's under your watchful eye! It's the ideal opportunity to empower her with information and strategies.
When she thinks she's ready to date, sit her down and map out the ground rules and consequences. Let her know your concerns. She may have no idea about the realities of date rape drugs, sexual violations, or what to do if her date gets behind the wheel after drinking.
Go ahead and bring up all the scary stuff. Help her troubleshoot what she would do if those things happen. Let her know that you will allow her to work her way up to a real 'date' in baby steps, so that by the time she is alone with a boy she'll be prepared to handle anything.
Let her start by with going out in a mixed gender group of friends. Then let her go on group dates, then double dates, then out for a dinner date alone (but in public!) After each date, debrief with her. Ask how it went, ask if there was any red flags or potential problems, and ask if she felt comfortable. In this way, you are helping her tune into her own gut instincts (and you want that since you can't be there to watch over her forever), and to identify her own readiness to take the next step (or not). You are also taking rebellion out of the equation. (it's hard to hear my protective gut instincts if I am busy sneaking out the window to prove that my parents aren't the boss of me!)
I issue a blanket offer to my kids: If your inner alarms go off at any time for any reason, you can call me and I will come and pick you up, no questions asked. I believe that is one of the very best insurance policies of all.
Your daughter needs your help. Teach her how to keep herself safe, and then let her practice her skills incrementally. You'll both be glad you did.