Strangely enough 777 I had a similar scenario last year. I assume you infer that the passenger has positively been identified as suffering a heart attack, there is no doctor on board and you have been reliabley advised (by the senior crew in charge) that the passenger will die if he doesnt get proper medical attention fast.
Ok the decision here is not wether returning back to the departure field is legal but do you believe it is safe for all on board if you attempt to do so after careful consideration of all factors. There is no sense in unrealisticaly putting everyone in a possibley hazardous high-risk situation (including you) for the sake of one.
[This message has been edited by Slasher (edited 16 May 2000).]