In an award dated 21 December 2020, the Tribunal in Cairn Energy v India concluded that India’s decision to impose taxes retroactively on the foreign investor violated the fair and equitable treatment (FET) obligation of the India–United Kingdom (UK) bilateral investment treaty (BIT). Hence, the Tribunal ordered India to return over US$1.2 billion to Cairn Energy. This case has attracted attention for reasons such as whether taxation matters fall within the scope of a BIT, whether the amendment of tax laws retroactively by a country could lead to an internationally wrongful act under the BIT and the interpretation of the FET provision.3 However, the purpose of this case comment is to analyse this case from the point of view of the International Law Commission Articles on State Responsibility4 (ILC Articles), which, over the years, have been widely referred to by investor-State dispute settlement (ISDS) tribunals.5 Thus, the comment discusses those aspects of the case that dealt with the ILC Articles.