Jargon File and the "back door"

The term that I found most intriguing on the Jargon File dictionary was the simple term "back door". The term itself is defined as following:
"Back door - a hole in the security of a system deliberately left in place by designers or maintainers. The motivation for such holes is not always sinister; some operating systems, for example, come out of the box with privileged accounts intended for use by field service technicians or the vendor's maintenance programmers. Syn. trap door; may also be called a wormhole. See also iron box, cracker, worm, logic bomb."

The term is intriguing in several ways. At first I did not think that the term was invented by hackers and I thought the term was invented by the mainstream IT industry as it is so commonly used. On the other hand - after thinking about it - who else could have coined the term better than the hackers themselves. The term is also intruiging in the sense that is directly related to the main topic of the course - ethics and law as in fact the whole IT ethics and law is in big part related to back doors. Is it ethical to create back doors , what to do if you have discovered the back door in someones system ? I would be interested to study this field more thoroughly - the ethics and law of "back doors".