Gibson Dunn & Crutcher is advising Facebook in the ongoing probe into its data protection breaches, as it faces a £500,000 fine from the Information Commissioner’s Office (ICO).

Co-chair of the firm’s international arbitration practice group, dispute resolution partner Penny Madden is leading for Facebook in London, following a report by the ICO that claims the social media giant broke data protection law when it allowed millions of users’ data to be accessed by consultancy Cambridge Analytica.

The scanty but “symbolic” £500,000 fine is the highest penalty possible under the pre-General Data Protection Regulation rules that apply in this case.

In April, The Lawyer reported that four firms had launched a case against Facebook and Cambridge Analytica, which threatened damages of more than $70bn. Squire Patton Boggs is understood to have been advising Cambridge Analytica. The firms were made up of London-based McCue & Partners, Washington DC firm Fields Law, technology and competition firm RuyakCherian, and Delaware-based Cross & Simon. They filed a a joint lawsuit on behalf of US and UK Facebook users in the District Court of Delaware against a number of defendants.

RuyakCherian managing partner Robert Ruyak commented that: “Facebook utterly failed in its duty and promise to secure the personal information of millions of its users, and, when aware that this stolen information was aimed against its owners, it failed to take appropriate action.

“Facebook must be held responsible for failing to protect its users’ personal information. We must also make certain that organisations like Cambridge Analytica and their benefactors – the Mercer family and Steve Bannon – are held accountable for this egregious theft and misuse and cannot further exploit it”.

Prior to Gibson Dunn’s latest partner promotions round, Madden was only one out of two female partners in the London office, out of a total partnership headcount of 28.

In November last year, two more female lawyers made the grade – finance lawyer Amy Kennedy and antitrust lawyer Deirdre Taylor. Herbert Smith Freehills energy partner Anna Howell also joined the firm in January this year, as the US firm’s first London-based oil and gas partner.