Abstract: Centering on the 12345 government service hotline,the Immediate Response to Public Complaints mechanism integrates public demands,compresses administrative response hierarchies and strengthens internal supervision and assessment.It has markedly boosted administrative response efficiency,yet reshaped the initiation pattern of administrative power and the structural framework of administrative legal relations in practical operation.Under its demand-oriented operational model featuring platform embedding and process governance,administrative legal relations are plagued by three prominent problems:complicated subject composition,blurred responsibility boundaries and the inward shift of the focus of rule-of-law supervision.Taking the primary interest attribute of public appeals and the structure of participating subjects as classification benchmarks,this paper conducts a typological analysis of legal relations in complaint handling.Such relations can be divided into private-interest and public-interest types,as well as bilateral and multilateral types,on the basis of which the rights and obligations of complainants,platform operators and competent handling authorities in different scenarios can be clarified.The legalization of the mechanism hinges on adopting typological approaches to specify the intensity of administrative response obligations,constrain the scope of administrative liability,and embed the new governance practice into the established administrative legal order.It ultimately realizes sustainable institutional equilibrium between responsive governance and administration by law.

Key words: Immediate Response to Public Complaints, administrative legal relations, allocation of rights and responsibilities, typological method, legalization