Judicial criticism of the quality of regulatory decisions and the enforcement processes of key regulators is prompting changes to regulatory procedure and policy.

In July, the European Court of First Instance (CFI) annulled the European Commission's (EC's) decision to permit a joint venture between Sony and Bertels-mann, the first occasion that a Commission merger clearance decision has been annulled. This was a real challenge to the EC's decision-making process following its overhaul as a result of a series of setbacks in 2002, when three high-profile merger prohibition decisions were annulled.

The CFI's verdict was a blow for the EC, but more worrying was the court's scathing criticism of the regulator's decision, which it said relied on contradictory evidence, demonstrated a "mani-fest error of assessment", and was not of the "requisite legal standard".

The treatment given recently by courts to other regulators has been no less damning. The Financial Services Authority (FSA) has suffered a series of defeats before the Financial Services and Markets Tribunal (FSMT), including the high-profile Legal & General case last year, in which it was criticised for "reaching conclusions not justified by the material before it", and the failed market abuse case this year against Paul 'the Plumber' Davidson, in which the FSMT expressed surprise that the FSA had even alleged that Davidson sought to conceal his spread-betting arrangements, given "much evidence to the contrary".

In August 2005, the Competition Appeal Tribunal (CAT) delivered a withering verdict on the OFT's infringement decision concerning the sale of betting rights by the Racecourse Association, concluding that the OFT's reasoning was a "triumph of theory over commercial reality". In two of the three OFT merger review cases heard by the CAT to date, the court has annulled the OFT's decisions and criticised its analysis.

Even in the US, where the criminal and regulatory authorities have employed increasingly aggressive methods against companies and their employees, apparently unchecked, there have been some indications of the courts showing an increased determination to reign in the authorities' excesses.

Earlier this year, the Manhattan Federal District Court severely reprimanded the Department of Justice in a tax shelter case against former KPMG partners, first for pressuring KPMG to not pay the defendants' legal fees, then for coercing two of the defendants to give statements.

The Legal & General debacle sparked the FSA's much-publicised enforcement process review, leading to a number of key changes, the most significant of which was the clarification of the separation between those who investigate a case (the FSA's enforcement arm) and those who decide upon the sanction (the Regulatory Decisions Committee). The EC, similarly, conducted a sweeping reform of its merger review procedures following the defeats it suffered in 2002, including appointing a chief economist to bolster the integrity of its economic analysis.

The question now is whether either review has gone far enough.

In part, this pattern of the judiciary setting the parameters of regulatory enforcement, and the thresholds required to be met, may be self-perpetuating, as judicial criticism of regulators may encourage further challenges. This effect is already being seen to an extent in the number of cases brought before the FSMT, which has shown itself to be a robust, independent adjudicator.

The impact of these developments on the regulatory environment is being felt. The increased threat of challenge is leading regulators to focus resources on investigating and prosecuting cases more thoroughly, and possibly to greater caution in deciding whether to bring enforcement proceedings. The EC has made clear that its resources are over-stretched and, along with national competition authorities, is seeking to encourage private enforcement in relation to anti-competitive agreements and abuses of market power, to enable it to focus on investigating the most serious infringements.

To maintain deterrence, regulators may also look to impose heavier sanctions. In June 2006, the EC adopted new fining guidelines, one of the stated aims of which was to increase deterrence, and in April 2006, the Serious Fraud Office announced that, for the first time, criminal charges are to be brought in the UK against five pharmaceutical companies, and nine of their executives, allegedly involved in cartel activity.

The FSA has also said it intends to come down heavily, particularly on senior management. In a January 2006 speech, director of enforcement Margaret Cole said the FSA will ensure that "financial penalties are fixed at levels that are sufficient to deter potential wrongdoers and where necessary we will increase penalties to achieve this".

The counter, in the long-term, to the willingness of the judiciary to hold up regulatory decisions to rigorous scrutiny and the consequent erosion of businesses' reluctance to challenge regulatory decisions, looks likely to be more rigorous regulatory enforcement and heavier sanctions.

Piers Reynolds is an associate in the litigation department at Allen & Overy.