Understanding the text in legal documents can be challenging due to their complex structure and the inclusion of domain-specific jargon. Laws and regulations are often crafted in such a manner that engagement with them requires formal training, potentially leading to vastly different interpretations of the same texts. Linguistic complexity is an important contributor to the difficulties experienced by readers. Simplifying texts could enhance comprehension across a broader audience, not just among trained professionals. Various metrics have been developed to measure document readability. Therefore, we adopted a systematic review approach to examine the linguistic and readability metrics currently employed for legal and regulatory texts. A total of 3566 initial papers were screened, with 34 relevant studies found and further assessed. Our primary objective was to identify which current metrics were applied for evaluating readability within the legal field. Sixteen different metrics were identified, with the Flesch-Kincaid Grade Level being the most frequently used method. The majority of studies (73.5%) were found in the domain of "informed consent forms". From the analysis, it is clear that not all legal domains are well represented in terms of readability metrics and that there is a further need to develop more consensus on which metrics should be applied for legal documents.

翻译：理解法律文件中的文本具有挑战性，这源于其复杂的结构以及包含领域特定的专业术语。法律和法规的制定方式通常要求读者接受过正式训练才能与之互动，这可能导致对同一文本产生截然不同的解释。语言复杂性是造成读者理解困难的重要因素。简化文本可以增强更广泛受众（而不仅仅是受过训练的专业人士）的理解能力。目前已开发出多种度量标准来衡量文档的可读性。因此，我们采用系统性综述方法，考察当前用于法律和监管文本的语言及可读性度量。我们共筛选了3566篇初始论文，发现并进一步评估了34项相关研究。我们的主要目标是确定当前法律领域用于评估可读性的度量标准。共识别出16种不同的度量方法，其中Flesch-Kincaid年级水平是最常用的方法。大多数研究（73.5%）集中在"知情同意书"领域。分析表明，并非所有法律领域在可读性度量方面都得到了充分体现，并且就法律文件应使用哪些度量标准达成更多共识仍有待推进。