Meet the woman taking on Silicon Valley tech giants — one fine at a time

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European Union Commissioner for Competition Margrethe Vestager is going after some of the world's most powerful tech companies for not sticking to the EU's rules.

Cases including Facebook's Whatsapp acquisition, Apple's unpaid taxes, and Google's search engine abuse have sent a clear signal to companies around the world that complying with EU rules is not just an option.

Speaking to CNBC in an episode of "Life Hacks Live," the former Danish politician fiercely upholds the EU rulebook for all companies, no matter their size.

"We can never compromise on quality because when living in a union based on the rule of law — and of course your right to defend yourself — the work is done thoroughly. Every fact is done the right way. We can never compromise on that."

European Competition Commissioner Margrethe Vestager speaks during a news conference at the EU Commission headquarters in Brussels, April 15, 2015.
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Vestager has become the face of these cases, coming under criticism for specifically targeting U.S. companies.

But the commissioner says she takes claims that she's anti-U.S. or biased "extremely seriously."

"Our badge is of neutrality, that you can do business in Europe — no matter your nationality, no matter ownership, no matter size — but you have to play by the book."

"We've been very thorough to say we have no biases, but you cannot have a job like mine without criticism," Vestager said. "There will always be people who disagree with you and that you have to learn to live with because otherwise I don't think that you can make it here."

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So when it comes down to it, when Vestager's sitting across from Apple CEO Tim Cook or talking to Google CEO Sundar Pichai on the phone, how does she act?

Vestager relies on preparedness and also a human touch.

"Know the case in question and what you're going to discuss also in some level of detail, but not necessarily so that you're just obsessed with the detail," she said.

"First learn the detail and then try to get another perspective, because you're going to meet another human being and you have to be present in the room."

"Digest the detail and then try to get the full picture," she added.

Life Hacks Live is a series produced by CNBC International for Facebook, where tomorrow's leaders get to ask some of the world's biggest influencers for advice. You can watch the full episode here.