Answer:
It's your personal choice. I think it's wrong to speak against wrong because you could be in any situation where your wrong, so in the end you would be hypocritical AND wrong :)
Or you could say it isn't wrong to speak against wrong because you could be objecting or putting someone to justice for their wrong doing. EXAMPLE: A murder trial and you are the victims lawyer ( the family of the victim's lawyer, because the victim is dead)
Hope it helps