In all aspects of what is termed consensual there is a risk of it going wrong.
Many, mainly playdocs, rely on a signature on a consent form or some other form of agreement of consensuality/understanding etc. They should note that this is next to valueless if there is a complaint of assault.
OK, it may go some way towards a defence to produce such a document but consider the situation in a purely sexual encounter, unrelated to medfet. What is acceptable and consensual one moment, might in a trice, become unacceptable! Even in a marital relationship, to force or even continue with an unwanted action will be considered assault or rape. How much more likely therefore is a complaint likely to be upheld in a relationship such as playdoc/patient who are otherwise strangers?
Of course, a good playdoc will sense if things are getting edgy and will call a halt before the patient does. Certainly the playdoc must STOP when that safe word is used.
But what about the situation when the playdoc does stop, either on request or on their own volition, but a complaint is still made? Well, they get to have to answer to it before a judge!
So, medfet activities, at whatever level, are fine and legal for as long as consensuality holds up. They are no longer legal when consent is withdrawn. But that does not cover the unthinkable!
The 'unthinkable' is when you both enjoy the play, no objections are made and indeed the play may be encouraged by the patient. Then the patient goes home and has a guilt attack - or relates the events to a partner. Yes! unthinkable isn't it?
There is no way a playdoc can 100% protect themselves from such a situation. You can go some way with the signature thing but, as above, its not foolproof even if the patient signs their real name, which isn't often! You can send a checklist of what is proposed and discuss the contents. I always insist on Q's and A's arising from that and keep the record. In IM chat I archive everything.
All of these things are helpful but NOTHING is foolproof. Use your gut instinct - be aware of temperaments and potential instability. If it doesn't seem right then don't do it - there will be another 'bus along shortly!
I don't think the matter of entrapment by the authorities is significant, at least in the UK. If the 'patient' complaining was to be a law enforcement officer and a record of conversations etc had been kept, then a prosecution would be unlikely to succeed or even take off. There are though the freaks and even potential blackmailers.
So when Protoc99 refers to consensual role play, when does consensual become non-consensual? Potentially at any moment and even retrospectively is the answer. And, erdoc, you'll see that 'what happens in Vegas' can rapidly become a headline in your local newspaper. vcr36056 - its true the same laws apply to dating but breaching them has the same consequences - so has not breaching them, but being accused of doing so! See my third paragraph.
Is it worth it? Yes of course it's damn well worth it. But playing safe is for both parties!