Conditional social assistance places a distinctive form of public power at the point where individual vulnerability and administrative authority meet. A claimant may be required to disclose information, search for work, attend training, accept suitable employment, or comply with other behavioural requirements; failure to do so can reduce the very resources used to secure food, shelter, health care, and other necessities. This article examines the legal limits of that power through a dialogue between contemporary proportionality analysis and Islamic legal thought on need, hardship, public welfare, and distributive responsibility. It argues that both bodies of law complicate the choice between unconditional assistance and unrestricted governmental conditionality. The relevant distinction is between conditions reasonably connected to overcoming or verifying need and measures that use deprivation itself as a disciplinary instrument. Drawing on social-rights law, administrative-law scholarship, empirical research on sanctions, and Islamic jurisprudential materials, the article develops a six-part public-law test: legality and scheme-related purpose; evidence-based connection; realistic capacity to comply; less harmful effective means; preservation of indispensable needs; and reasoned, individualised review. Proportionality is therefore used here not as a claim of doctrinal identity with maqāṣid or maṣlaḥa, but as a contemporary structure of public justification through which Islamic concerns about necessity, hardship, and human welfare can be made legally reviewable.