The principal objective of this study was to undertake a comprehensive and systematic examination of legal English through a tripartite analytical framework: tracing its historical development across temporal boundaries, critically evaluating the efficacy and limitations of corpus-based methodologies in diachronic linguistic analysis and exploring the increasingly significant role of artificial intelligence in legal language processing and interpretation. Through rigorously addressing three interconnected research questions, this investigation has not merely illuminated the multifaceted, inherently conservative, yet incrementally evolving nature of legal discourse, but has also critically underscored the persistent and multidimensional challenges inherent in enhancing clarity, accessibility and inclusivity within legal communication. These findings carry profound implications for our understanding of how specialised registers adapt to societal pressures whilst maintaining their functional integrity.