Introduction: Developmental language disorder (DLD), difficulties with using and/or understanding language, is highly prevalent in young offenders but is often undiagnosed. Even if there is a DLD diagnosis, it may not be deemed relevant to disclose to jurors. This study aimed to investigate whether the provision of a diagnostic label and information about DLD influenced mock juror perceptions of a young defendant. Method: Following the method of Maras et al. (2019), 158 participants read a fictional case study of a young defendant who was in court after assaulting a police officer in a misunderstanding at a train station. Half (n = 79) of the participants were informed that the defendant had DLD, and half (n = 79) were uninformed. Participants rated the defendant on his credibility (cognitive functioning, honesty and likeability) and culpability (blameworthiness, guilty verdict and sentencing leniency). They also indicated whether they thought the defendant committed the crime because of the situation he was in, because he was a bad person or both. Participants were asked to explain their reasoning behind each rating. Results: Participants in the informed condition viewed the defendant as significantly more credible and less culpable and were less likely to assign him a guilty verdict. Content analysis revealed four themes: anger, mitigating factors, communication, and situational context and police officers. Participants in the informed condition were more empathetic towards the defendant on all themes. Conclusion: Findings highlight the need for better detection of DLD in young people standing trial alongside the value of providing jurors with a defendant's diagnostic information.