It is a misconception that magic is intrinsically black or white. Magic is a neutral force dependent on the will of the person using it. It follows from this that there is no such thing as ”black magic” (except those lovely dark chocolate boxes around in the eighties - yummy! See my pic!!)
Magic can be used for the advancement of good or the advancement of evil. Chances are that as no person is entirely good or evil, magic is used for a blend of positive and negative intentions, dependent on the desire of the person casting the spell.
Individual practitioners of magic will each have their own personal rules for how they work. A Wiccan who subscribes to the Wiccan Rede (“An it harm non, do what ye will…) will be unlikely to use a spell that causes harm. A non Wiccan witch may use a broader range of spells including those popularly termed “black magic” such as curses, hexes and binding spells. All witches will be guided by their intention, their own view on morality and their comfort level for each type of magic.
Speaking personally, as a non Wiccan witch I would employ magic for whatever need suits my purpose at the time. I would however adhere to my own personal moral code (“Do what you believe to be the right thing and trust yourself”) to ensure I believed what action I was taking through my magic was the right action.
Image - unable to credit photographer