Procedural law on the international plane, especially the law applicable to international judicial proceedings, has long tended to be the poor relation of substantive law. In particular, insufficient attention has often been paid to its sources, and to the manner in which it may be created; and confident assertions tending to confuse the Sollen with the Essen, lex lata with lex ferenda, have been made with a frequency not to be expected in other fields of international law. Hence the common temptation to model international procedural norms or rules on what are perceived to be analogous dispositions of municipal procedural law, without taking sufficient account either of the degree of generality, actual or potential, of the municipal law rule, or of the accuracy of the analogy involved in its transfer to the international plane.