Objectivity and of justice: A critique of Emmanuel Levinas' explanation

For Emmanuel Levinas objectivity is intersubjectively constituted. But this intersubjectivity is not, as in Merleau-Ponty, the intercorporeality of pe rceivers nor, as in Heidegger, the active correlation of practical agents. It has an ethical structure; it is the presence, to each cognitive subject, of others who contest and judge him. But does not the exposure of each cog nitive subject to the wants and needs of others result in the constitution of a common practical field, which is not yet the objective world of scient ific cognition? For Levinas, the constitution of a world common to all is g overned by the practice of justice. Justice begins when above the self and the other there intervenes a third party, who contests and judges both. But whether this third party is a representative of humanity, or a figure of G od, would not his justice be but the name of higher egoism?