The Laws of Magic

The Compact of Babylon was an alliance forged in Babylon in around 1700 BC by several disparate magical traditions. It drew in mages from the Middle East, South Asia and the Mediterranean to that bustling city, where they shared their knowledge and practices with one another. This Compact is commonly regarded as the origin of the Orders of Atlantis, the largest body of mages in the modern world, though the Compact would evolve several times before it would became the modern Atlantean Orders, incorporating dozens of additional traditions over the ages and expanding their membership across the globe.

One of the lasting legacies of this meeting in Babylon was the establishment of the Laws of Magic, which laid out the various traditions' interpretations on how magic should and shouldn't be used--in effect what constituted acceptible use of the arcane, and what was black. These laws were actually inspired by earlier Atlantean laws, though interpreted through the contemporary lens of mages living in the Age of Magic. Since their establishment, these laws have been revised several times, and today, they number seven:

• Do not engage in blood magic. Taking the life of another, or even harming them, to power your spells is considered addictive, tempting one towards ever greater depravity.
• Do not flow against the streams of time. Time travel can create paradoxes, and paradoxes do horrible things to the stability of the reality. Just ask the Isle of Avalon--oh wait, you can't, because it got paradoxed out of our space-time continuum.
• Do not consort with demons. Demons are nigh-universally evil and looking to tempt you down the dark path to sin. Generally, any act which contacts a demon is seen as gambling with your immortal soul.
• Do not dominate another's mind. Mind control, and the usurpation of free will, is another one of those slippery slopes, as well as once again directly harming another individual. However, binding one through pacts and promises are allowed, which still allow the fey to run amok doing their things, and for mages to continue to bind supernatural creatures to their will. This prohibition generally includes magical torture and other means of bending others to the mage's will--consent for bindings must be freely given.
• Do not interfere with the boundaries of life and death. Generally, raising people from the dead is bad, binding dead souls and ghosts to your will are bad, placing death curses on others is bad, seeking immortality through lichdom is bad, and interfering with the proper flow of souls through the underworld is bad. Let the dead manage their own affairs, while the living manage ours. This typically limits necromancy to summoning willing shades, conversing with corpses, animating mindless skeletons, and entropic hexes.
• Do not interfere with souls. Nobody really knows what souls are, but they are powerful, and a skilled warlock can harvest souls to increase their arcane might. However, souls are also the source of a being's free will, their ability to use magic. Indeed, most supernatural creatures--fey, angels, horrors, jinn, ghosts and demons--are nothing but souls. Messing with souls can strip someone of their free will, slaughter them outright, grant you immortality at the cost of others' entire existence, or grant you the magical equivalent of a nuclear weapon. Thus, any attempts to mess with souls are typically frowned upon.
• Do not pierce the barrier to the Outside. Seriously, don't. Unless you want our world to die screaming under a sky filled with tentacles, it's a really, really, really bad idea.