The continual availability of energy is economically and socially essential, but is primarily reliant on private operators and investments to be maintained and developed. Investments in the energy sector are typically highly capital intensive and require long payback periods. This in turn calls for legal and regulatory stability for such investments by the legislator. While changes to laws are inevitable, such changes should be implemented prospectively and take into account the legitimate expectations attached to existing investments. In this article we analyse the recent practice of the EU to retrospectively apply legal rules in the energy sector. Our research shows that it has been common practice of the EU to grant transitional periods and grandfathering rights to allow market participants to adapt to the ‘new rules of the game’. However, while this represents common practice, our research shows that this practice is applied with discretion and can even be misused in the pursuit of political objectives, violating established legal principles including legitimate expectations and legal certainty.

持续的能源供应在经济和社会上都是必不可少的，但主要取决于私人运营商以及要维持和发展的投资。能源领域的投资通常是高度资本密集型的​​，需要较长的投资回收期。反过来，这需要立法者对此类投资的法律和法规稳定性。尽管不可避免地要修改法律，但这种修改应在未来进行，并应考虑对现有投资的合理期望。在本文中，我们分析了欧盟最近在能源领域追溯适用法律规则的做法。我们的研究表明，授予过渡期和祖父权利以允许市场参与者适应“新游戏规则”是欧盟的普遍做法。然而，