This is a great question to ask during an interview and it is an excellent opportunity for the candidate to demonstrate an appropriate level of professional assertiveness. The best way to answer this question is to site a real experience.

1. State the situation that caused you to have to speak up and a little background to the situation.
2. Then state the actions you took in order to be heard.
3. Then it is very important to clearly state the outcome or result of you speaking up.

If you don’t have a real, professional experience, then you can perhaps state a time when you had to do this in your personal or recreational life. Use the formula above.

If you don’t have any real experiencing speaking up then this might be a tough question to answer. My advice would be telling the interviewer that you can’t recall a recent time requiring you to have to speak up, but if the occasion were to present itself you would (and then give an example based on 1 – 3 above).

Here is an example from my past using the three step approach above.

I was the marketing manager reporting to the CMO at my last company and several executives had their own agenda about the timing of key projects. I knew that if one particular project didn’t get the priority then all other projects would suffer based on key dependencies. Whenever I was in a meeting with all the executives to discuss project priority it didn’t appear that anyone was listening to anyone because each of them had their own unique sense of urgency to prioritize their projects.

I knew a heated meeting wasn’t going to get my voice heard, so I met with my CMO one-on-one and put together an easy to follow matrix showing that if this particular project wasn’t implemented first that his project couldn’t be successful. When I realized I had his full attention, I then demonstrated why the 4 other projects were dependant on this particular project as well. I asked permission to meet one-on-one with each executive to help prioritize this project so it could get started immediately.

With permission, I met with each of them and there was finally a consensus about which project needed immediate priority.

Tammy is absolutely right. It's a great question, and one that we should all be prepared to answer.

As in all of the 'behavioral' interviewing we see so much these days, some advance preparation is critical. Each job seeker should have 3-5 good success stories ready to help them illustrate their branding to the interviewer. I feel the best preparation is to write it out, then practice telling the story until you have it truly internalized.

I prefer the PAR format as a good structure for writing your stories, and always have a title or headline so they are easy to remember:

P - Problem
A - Action
R - Result

I like the PAR format, because it is a constant reminder that employers need problem solvers.

Lastly, if you can't answer this question, it is probably a good indicator that you need to be more assertive. You deserve to be heard, and your employer (client) hired you to help solve problems. You owe it to yourself and them to give it your best.

Both of the above are great answers. My only additional advice is to also talk about listening to understand completely before any such assertion. Cite Stephen Covey if you'd like; "seek first to understand, then to be understood."