The first D: Direct
This is what it sounds like: you intervene directly. For instance, if someone makes a racial comment or an insensitive joke, you could say, “Come on, Alex, that wasn't appropriate and comments like that don't belong at work."
Direct intervention is the most challenging and generally feels the most unsafe for the person intervening. Remember what we stated above: take time to consider the nuances of the situation. Use this approach only when you feel it is safe and appropriate to do so.
The second D: Distract
You may have heard stories about this technique. For instance, a woman is being harassed on the subway. A witness (bystander!) notices what’s happening, and, despite being a complete stranger, rushes over and says, “Hey, Annie, so good to see you! How are you, What’s happening? Where are you headed?”
A work example might be if you see or overhear something that doesn’t sound right to you in a neighboring cubicle or office. You can make up an excuse to stop by and ask a question or request a quick meeting.
By intervening in this way, you give support to the person being harassed, and you make it much more difficult for the harasser to continue their bad behavior -- in that moment anyway.
The third D: Delegate
In situations where you feel uncomfortable intervening, even with a Distracting tactic, you can delegate remedial action by advising the target of the bullying or harassing behavior to report it to Human Resources or to another senior-level manager. You can further show your support by offering to go with them when they make their report.
And don't forget another "D" that goes with all 3 options: Documentation
In all cases, remind the target of the bad behavior to document what happened, who was involved, the time and location it occurred, and the names of anyone who witnessed the event. Human Resources will need this documentation if and when they choose to take disciplinary action.