Vice President Leni Robredo is the second-highest elected official in the Philippines, a country where the president and vice president are elected separately. The vice president takes over should the president die or become incapacitated.

Robredo is probably the most contested politician in the Southeast Asian nation as she is a critic of the incumbent President Rodrigo Duterte and his policies, particularly his brutal anti-drug mission that has cost thousands of lives. Over 3,800 Filipinos have been killed so far as part of the campaign.

Read more: Rodrigo Duterte under attack by 'Temperamental Brats'

While security forces claim the deaths occurred in their attempt at self-defense after armed men resisted arrest, critics bemoan the climate of impunity and accuse that executions are taking place with zero accountability. The killings appear to have dented the approval ratings of Duterte, who has enjoyed widespread popularity since winning the presidency last year.

Meanwhile, the son and namesake of late Philippine dictator Ferdinand Marcos declared last week that he was confident of ousting Vice President Robredo in a legal challenge. Ferdinand Marcos Jr. narrowly lost to Robredo in the vice presidential election last year but he filed a case with the Supreme Court alleging she cheated by manipulating computerized vote counting machines.

Talking to DW, Robredo says she is confident that the Supreme Court will rule in her favor. She also hopes people will continue to remain vocal against extrajudicial killings in the country, because she believes that's the only way to stop these deaths.

DW: The Philippines has an unusual set up where the president and the vice president are elected separately and usually belong to two different political parties. What is it like working under that arrangement?

Leni Robredo: It is difficult. For a long period of time, the president and the vice president would come from different political parties but managed to work hand in hand. In all honesty, I thought the president and I could work it out. It was obvious that we were coming from different points of view, but there were many points of convergence that we could agree on like, for example, when he appointed me to be head of the Housing and Urban Development Coordinating Council.

Read more: Will the ICC prosecute Philippine President Duterte?

Read more: Why is Duterte so popular in the Philippines?

If you are a member of the cabinet, you cannot disagree with the president publicly. You are supposed to be the alter ego of the president. But there were always issues that came up and I could not help but speak up. There were one or two cabinet meetings when I said, "Thank you Mr. President for not taking it against me if I have taken positions contrary to yours." I don't remember anymore but he said something like: it was all just work.

I really thought there was a chance that we would be able to work alongside each other. But I was shocked when I was asked not to attend cabinet meetings through text message. I tried to get a direct order from him but I was not able to get through.

In my team, there were differing opinions. Some said I should still continue to attend cabinet meetings because I have a mandate to do my job. But if I had continued to stake it out without the confidence of the president, it would be equivalent to sacrificing the housing sector. It would be better if he hired another full-time housing sector head so the sector would not be marginalized. It has been difficult, but I think we made the right decision.

Extrajudicial killings related to the war on drugs continue to be a contentious issue. Recently, the Philippine National Police released the result of their investigation saying there had been only one extrajudicial killing. Foreign Affairs Secretary Alan Cayetano has said that the more than 3,800 people killed in anti-drug operations were all criminals. How do you view this issue?

I have always been vocal about extrajudicial killings from the very start. The worst bashing I got was when I became very public about it. The threat of impeachment started with my video message to the United Nations speaking against extrajudicial killings.

There were just a few of us speaking out against extrajudicial killings then, even though there were so many opportunities to do so. If we had given it the kind of importance it deserves, we might have been able to prevent carnage of such scale.

Over the past couple of months, after the death of Kian de Los Santos, a lot more people have become more open and vocal. I hope that continues because that's the only way we can stop these killings. Silence is one of the factors that allow them to continue.

President Duterte's approval ratings have dipped by about 18 points in recent months. What do you read into that?

I try to keep quiet most of the time because when I speak up, the issue will be diluted. Critics will say that I'm rushing to take over the presidency or that I stand to benefit from this news. Instead of me being the face of opposition, I am hoping that public opposition will be an organic reaction to important issues.

You beat former Senator Ferdinand Marcos Jr. by over 200,000 votes in last year's vice presidential election. But he continues to contest your win. Recently, he said that he will be vice president by the end of the year. What is your take on this?

He has been saying that since last year. He has been making a lot of statements which, over time, have been proven false. The evidence will speak for itself.

Still, the Marcos family has the machinery, the money, the connections and the support of this president.

I think it's a very real threat but I don't want to lose hope in the Supreme Court. People are saying the judges might be swayed but I still think that at the end of it all, the Supreme Court will decide in our favor. He has no basis. I don't see any reason why the court will go with them and decide against us.

Leni Robredo has been serving as vice president of the Philippines since June 2016.