In 1995, I went to Kikwit in the Democratic Republic of Congo, then Zaire, to produce a documentary on the Ebola outbreak. When I arrived, news teams from all over the world were clamouring to get inside the ward. But local and international medical staff refused to let any journalists in. Victims were dying a terrible death, and doctors were concerned for their dignity - and for the safety of reporters. I heard that one major American network's cameraman tried to force his way in. He was jostled by a doctor, fell to the ground and scraped his elbow on the cement floor. Suddenly, he panicked at the possibility of contracting Ebola.

I had the luxury of hanging around long after reporters went off to cover another story. I was able to cultivate relationships with staff until they developed enough trust in my story. I earned the right to film in the ward, to get to know the patients and to get the footage I wanted.

Dutifully, I asked all the patients (or their family members, if they were too sick to respond), if they were okay with my shooting footage of them. Invariably they said "yes," but was it truly informed consent? This is Africa, and the reality is that none of them would say no to a white person. Being surrounded by white doctors and scientists, there was an assumption that I was in some way associated with the team that was there to save them.

Journalistic ethics require that we act as moral individuals and professionals. I asked myself three questions: Are these images integral to telling the story? Can I use these images in a way that is respectful to the people I'm filming? Am I doing this without harming the people I'm filming? At the time, the answer was yes to all three questions.

But deep down, I also know journalists go after stories with the goal of "seeing it all," and this desire can influence us into making self-serving decisions. When I started making documentaries, I thought if I was able to tell an honest and balanced story, I could bring films with a clear vision and a conscience to my audience. But once I'd been in the field for a while, I realized that ethical issues would force me to consider my influence on subjects and my responsibility to those watching my films. My Ebola encounter profoundly changed the way I viewed myself as a "director," as did another, radically different experience.

Recently, I produced and directed a documentary called Sex Slaves, about the trafficking of women from former Soviet bloc countries into the global sex slave trade. I wanted to take people inside the world of trafficking. I wanted to compel people to feel the horror so that they might be motivated to act - to donate money or to pressure their governments into taking action. The best way to get inside was to go "undercover" with hidden cameras.

The rules of engagement seemed clear. There was no way we could film these people openly - they were engaged in heinous criminal acts - but it was in the public's interest to see how trafficking works and how these people prey on the vulnerable. Though there are many debates about covert filming, I had no qualms in this context. Other issues that weren't so clear-cut surfaced on location, though.

The film follows the unfolding story of Viorel, a Ukrainian man whose pregnant wife was sold for $1,000 to a notorious pimp in Turkey. When I met Viorel, he had just returned from an unsuccessful mission there, posing as a trafficker to try to buy his wife back. He told me he was going back to try again. When we offered to document this second attempt to free his wife, he was openly enthusiastic. Suddenly, he had a support system.

One issue I didn't anticipate - perhaps naively - was that our relationship with Viorel wouldn't allow for the comfortable distance my crew usually maintains with subjects. We were no longer observers, but participants who could influence the story's outcome. Viorel sought our advice at each stage of the search. He began to relate to us not as journalists, but as partners in a mission. Ultimately, the only way to acknowledge this behind-thescenes relationship was to film it. We ended up in the film.

Another issue came up when Viorel set up a meeting with the wife of the pimp who forced his wife into prostitution. Our plan was to follow him with hidden cameras and get the meeting on tape, and we were successful. Now we had proof that Viorel's wife was being held, that she was forced into servicing clients and that her captors had paid off the police for information. Yet Viorel was no closer to getting his wife back.

Out of desperation, Viorel decided he wanted to use our incriminating undercover footage to threaten the pimp. This made me extremely uncomfortable. Did I have an obligation to use it to help him? Would I be responsible for putting him, his wife and, frankly, my crew in more danger? My crew and I discussed this at length and concluded that the stakes were too high - using the footage might do more harm than good for Viorel and his wife. He was quite upset, but I'm convinced we made the right decision.

Because we'd become part of the story, we felt this enormous weight of undeserved power. We also found out how dangerous that power can be. Luckily, the pimp eventually released Viorel's wife. She believes her husband's ability to apply pressure on the traffickers had an effect. Viorel believes he couldn't have done it without us.

Unlike many other professionals, journalists in the field are pretty much on their own when facing ethical considerations. It's important to ensure that our ambitions as professionals don't conflict with our responsibilities as human beings.

Ric Esther Bienstock is an award-winning independent documentary filmmaker based in Toronto. Her most recent film, Sex Slaves, was produced for CBC and Canal D in Canada, Channel 4 in the U.K. and PBS's Frontline Series in the U.S.