This article examines national human rights institutions (NHRIs) as part of the evolving fourth-branch considerations within contemporary constitutionalism. Critically engaging with recent scholarship on fourth-branch institutions, it argues that, in general, NHRIs satisfy the criteria of double constitutionalization – as constitutionally entrenched entities and as protectors of constitutional rights. Through comparative analysis of ombuds institutions and human rights commissions, the article evaluates their mandate and functions against the existing criteria for fourth-branch actorness, particularly focusing on determining norm breaches and interpreting norms. The article argues that while NHRIs’ constitutional design and unique international peer review accreditation suggest significant independence, their de facto performance often depends on volatile political and institutional environments. The empirical discussion in the article exposes how appointment procedures, budgetary control and political capture can undermine their constitutional promise. The article concludes that NHRIs occupy a liminal constitutional space – formally insulated from party politics but deeply implicated in high politics – and that their credibility rests on maintaining a precarious balance between independence and accountability. In doing so, it advances the theoretical and comparative understanding of NHRIs as core protectors of constitutional rights within the broader fourth-branch paradigm.