Apple inc (NASDAQ:AAPL) has reportedly said that the European Union’s order for it to pay 13 billion euros ($14 billion) in back taxes “defies reality and common sense”.

The iPhone maker is currently appealing to Europe’s second highest court to overturn the European Commission’s 2016 ruling that it pay the record sum to Ireland, with that member state – whose economy has been boosted by investment from multinational companies due to its low tax rates – also challenging the EC decision.

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Apple’s appeal to the General Court came after the EU executive in 2016 said the tech giant benefited from illegal state aid due to two Irish tax rulings which artificially reduced its tax burden for over two decades.

Reuters reported that Apple has accused the Commission of using its powers to combat state aid “to retrofit changes to national law”, in effect trying to change the international tax system and in the process creating legal uncertainty for businesses.

The EU executive has dismissed the arguments, saying it was not seeking to police international tax laws and accused Ireland of not having done its homework when assessing Apple’s taxes, Reuters added.

The newswire said Apple’s chief financial officer Luca Maestri led a six-strong delegation to the court where a panel of five judges will hear arguments over two days.

The European Competition Commissioner Margrethe Vestager has spearheaded a campaign against international companies such as Apple, Amazon Inc (NASDAQ:AMZN) and Starbucks Inc (NASDAQ:SBUX) and others.