The first significant encounter between the newly elected Parliament and the future European Commission will come this autumn. It is then that the national nominees for commissioner will be subjected to tough public cross-examination by MEPs on their suitability for the post and potential portfolio.

This will be the sixth time that the Parliament has held confirmation hearings for new commissioners. On each occasion, it has used the procedure to exert extra influence over the incoming Commission. Indeed, given that MEPs cannot censure individual commissioners once they are in office, this is the only opportunity they have to decide the fate of specific nominees. It is a political power they have not been afraid to use, leading to the rejection of three candidates in the past five years.

The procedure forces the future commissioners to master as much of their portfolio as they can before taking office. They will spend the time between their nomination and the hearings being briefed by officials on the policy area which the Commission president, usually after careful consultation with national governments, especially the larger ones, has allocated them.

At the same time, the parliamentary committees draft detailed questions that must be answered in writing, invariably by Commission officials, but in the name of their future political master. These give MEPs a flavour of the approach an individual commissioner will bring to his or her new task. The real test then comes with a three-hour hearing, when nominees have to appear before the committee covering their policy area and answer questions on a wide range of issues.

The innovation, which was introduced by the Parliament’s then President, German Socialist Klaus Hänsch, was first used in 1994. There were two main highlights. The first was the distaste the former French Prime Minister, Edith Cresson, displayed to being questioned by MEPs – a hostility that rebounded on her when she was the main reason the Commission had to resign almost five years later. The second was the ambush by members of the women’s committee of the Irish Social Affairs Commissioner, Padraig Flynn, for what they considered to be disparaging remarks he had made when Mary Robinson was running as the first female president of Ireland.

However, all nominees were approved, as they were five years later, in 1999, when a new phenomenon appeared: political opponents used the European stage to refight domestic political battles. On this occasion, it was Philippe Busquin, Belgium’s French-speaking commissioner, who was targeted, unsuccessfully, by Flemish Christian Democrat MEPs for his weak command of Dutch.

It was in 2004 that the confirmation hearings came of age. The procedures for the commissioners from the ten new member states passed off uneventfully before the summer, but it was in the autumn that the parliament showed what a strong political weapon they could be.

Rocco Buttiglione, a former Italian European affairs minister, who had been slotted in for the sensitive justice and home affairs portfolio, outraged large sections of the Parliament with his staunchly Catholic views on homosexuality and the role of women in society. While some respected his beliefs, the majority felt they would adversely affect his work as a commissioner. The Latvian nominee, Ingrida Udre, who had been given the taxation brief, also came under fire over allegations of financial irregularities in the funding of her political party. The strong criticism forced both to stand down.

MEPs were also distinctly unimpressed by the performance of László Kovács, the Hungarian foreign minister who was due to be responsible for energy policy. In the end, their doubts forced the incoming Commission President, José Manuel Barroso, to reshuffle responsibilities by entrusting energy to the new Latvian nominee, Andris Piebalgs, and giving Kovács taxation. Just over two year later, the hearings claimed another victim when doubts over his financial background forced Romania’s initial nominee, Varujan Vosganian, to withdraw.