unified conflict of law rules in international trade contracts

Enter into of every international contracts is the confluence of different legal systems that these differences lead to challenges and uncertainties regarding the governing law. Therefor we need instruments to materialize two principles of speed and security in such contracts. Among these instruments, unified conflict of law rules could be a guide for the parties, arbitral tribunal and courts of justice in determining the governing law.
These rules bring an end to claims of different legal systems to govern the contract, make predictable the rights and obligations of the parties, prevent conflicting interpretations through unification of rules on conflict of laws and prevent imposition of stronger party law to the weaker party and so on. But these rules are not free from criticism. For example all of the related legal systems do not participate in codification of these rules equally.