Not to mention that taxing specific companies that happen to come from the same country while the keeping the tax rules unchanged for the rest of the economy isn't fair or free trade and would justifiably require retaliation.
The tax law is also not applicable only to US companies but to all companies.
This is like saying all law breaking mafia members that corrupted a member state are coming from the same country and putting them behind bars is not fair because the EU is a consolidated market and if you want to profit from it you have to agree that the mafia extracts value from the arrangement and leaving the rules unchanged for the rest of the non-mafia economy is not fair or free trade.
"The ECJ will decide the case and unless the EU wants to undermine the entire system of transfer pricing which is the basis for international trade, they will side with Ireland and Apple."
Transfer of profit to the lowest tax destination is not the basis for international trade. Evading taxes will result in tax laws adapting.
The US is not the lowest tax destination - in fact it has a relatively high corporate tax rate. Apple is making their international profits subject to US corporate tax which is why the US is on the side of Ireland and Apple in the appeal.
There is no corporate tax evasion here and that is confirmed by reports like this one[1] which makes it clear that offshore Apple (and other US corporation) profits are clearly liable for US corporate tax. The fact that they can defer paying their US corporate tax is due to a quirk of the US tax system and nothing more.
[1] https://seekingalpha.com/article/4150066-repatriation-make-2...
The 3% is a proposed duty/tarif which has nothing to do with how Apple's profits are and were taxed. This is a tax on revenue/sales/imports not on company profits.
That aside: Ireland has a lower corporate tax rate than say france, so for example a soap company based in ireland doing business in france pays the irish corporate tax rate, it's not illegal and they're not part of the "mafia", now the EU is saying that soap companies will have to pay 3% tax on soap sold in france (in addition to VAT) further still they have no problem with non soap companies and that it's a coincidence that most soap companies affected come from the same country.
https://www.cnbc.com/2016/08/30/how-apples-irish-subsidiarie...