Having been issued the penalty last month, the tech giant is disputing it on the basis that the UK data watchdog's investigation into its business found no evidence that data from UK users, harvested by Dr Aleksandr Kogan, was among the 87 million profiles harvested for political gain.
Facebook's associate general counsel for EMEA Anna Benckert said:"The ICO's investigation stemmed from concerns that UK citizens' data may have been impacted by Cambridge Analytica, yet they now have confirmed that they have found no evidence to suggest that information of Facebook users in the UK was ever shared by Dr Kogan with Cambridge Analytica, or used by its affiliates in the Brexit referendum."
She argued that the core of the ICO's argument no longer relates to the events involving Cambridge Analytica.
"Instead, its reasoning challenges some of the basic principles of how people should be allowed to share information online, with implications which go far beyond just Facebook, which is why we have chosen to appeal."
Benckert's point of principle is that the same rationale that the ICO is using to fine the company would also mean that it would breach data protection guidelines “to forward an email or message without having agreement from each person on the original thread."
She added: "These are things done by millions of people every day on services across the internet, which is why we believe the ICO’s decision raises important questions of principle for everyone online, which should be considered by an impartial court based on all the relevant evidence."
Facebook caught a break from ICO in that its misgivings fell under the remit of the 1998 Data Protection Act and not the European level GDPR which carries a maximum fine of 4% of global turnover – equivalent in Facebook’s case to £1.4bn.
When ICO imposed the maximum penalty possible on Facebook, it was on the basis that UK members had been put at risk and the social network had not done enough to address this after learning of the problem. It did admit that its own investigation found no evidence that UK citizens had fallen victim to Cambridge Analytica's data capture.
ICO has yet to issue a statement, but it has acknowledged the appeal.