General Order 2 according to Alpha/Beta is pretty straightforward:
Starfleet regulation against the taking of intelligent life.
It's pretty vague and there's not much to go by here for situational reasons, but I did find something a little more concrete in the Star Trek Minutiae
No Starfleet personnel shall unnecessarily use force, either collectively or individually, against members of the United Federation of Planets, their duly authorized representatives, spokespersons, or designated leaders, or members of any sentient non-member race, for any reason whatsoever.
This one sounds a lot more reasonable, though we can't be sure since there's no canon source for this one. However, another site, Starbase 118
, uses the same definition for theirs.Federation Sim Fleet
uses a similar definition, but elaborates it with stipulations:
General Order 2: Under no circumstances, shall an officer of Starfleet willfully inflict harm or injury on any lifeform without the authorization to use force from a commanding officer, unless it is the final recourse to justly save one's own life or the lives of others when General Order 1 is not warranted.
This one is similar to ours, but with better wording.
From Reddit, /u/bremo93 from the Star Trek's board made his own Starfleet Regulation Handbook
that he gleaned off of sources found on the web. Order 2 is the same definition as Star Trek Minutiae and Starbase 118's.
I seriously think bremo93's regulation handbook is the best, closest thing I've seen to canonical orders and regulations.