Abstract The article examines the challenge of balancing security restrictions with the need for transparent and democratic legislative functioning. It begins by highlighting the importance of transparency and its relationship with democracy and good governance. Using Ukraine as a case study, the article reviews the open data and other transparency measures employed by Ukraine’s Parliament before the onset of the full-scale Russian aggression on February 24, 2022. It then discusses the limitations imposed on these measures following the declaration of martial law, the ensuing public debate, and subsequent modifications to specific transparency restrictions. Through concrete examples, the paper argues that a lack of transparency and the failure to balance security limitations with public demand for openness can undermine the parliament’s legitimacy and constitutional authority. The article concludes that security measures must be proportionate and regularly updated to preserve the integrity of parliamentary democracy and the constitutional role of the parliament.