Nigel Foster. EU Law Directions 6 ed. 2018. p. 239
Case 294/83 Parti Ecologiste Les Verts v European Parliament and the EU Treaty extended the list of reviewable acts to those of the EP that give rise to legally binding effects on the position of third parties, in this case concerning a budget decision of the Parliament sharing out of the budget among the party groupings.
In Case C-106/96 UK v Commission, the Council had decided not to support ‘Poverty 4’, a programme to combat poverty and social exclusion, but the Commission decided nevertheless to fund a number of projects amounting to an expenditure of ECU 6 million and issued a press release to advertise this. If the last case looked a bit like sharp practice, this one looks even more deliberate and helps us to understand why the Commission is criticised in some quarters. The CoJ held that the Commission lacked the competence to commit the expenditure and the decision was annulled. However, in view of the fact that much of the expenditure had already taken place, the Court decided, in the interests of legal certainty, to exercise the discretion given to it under Article 231 EC (now 264 TFEU) and rule in favour of the payments made or promised.
I read Wikipedia's article. I'm too uneducated about the Functioning and Powers of the EU Parliament, and don't understand the facts. Pls ELI5?