Final answer:
Legislatures may avoid retroactive application of reforms to avoid legal challenges, uphold the reform's original intent, and manage practicalities. Retroactivity increases complexity and could undermine both legal stability and the purpose of the reform. Special interests might also lobby against retroactivity to maintain status quo benefits.
Step-by-step explanation:
The question as to why the legislature might choose not to make certain reforms retroactive is multifaceted and dependent on the specific context of the reform. However, a common reason is that retroactivity could create a range of legal complexities and challenges. This is because applying laws retrospectively can impact the stability of the legal system and potentially infringe upon individuals' rights who relied on the previous laws when making decisions. Additionally, the purpose of the reform itself may be compromised if changed retroactively, especially if it was designed to alter future actions and decisions rather than those in the past. Another factor to consider is the practicality of implementation. For significant reforms that require extensive new bureaucracy or changes at the state level, retroactivity could dramatically increase the administrative burden and associated costs. Finally, in the context of lobbying and political influence, it's likely that special interest groups may advocate against retroactivity to preserve the advantages they had under the old law.