I think, on reflection, that the term "Alien" is taken in it's original legal meaning and not it's contemporary Science Fiction meaning.<br/><br/>Alien actually means "From a foreign country", and only in recent decades has the alternative meaning of "Extra Terrestrial Being" been added.<br/><br/>As all Star Fleet personnel are<em>de facto</em>citizens of the United Federation of Planets, they are not "aliens" to each other. I'm pretty sure the directive refers to having sex with that rather strange looking plant-creature that we just encountered on this new world we've found. Tentacle hentai not withstanding, the chances are that if you're just a member of the Away Team Security Detail, the plant is going to eat you!