The primary responsibility of the judicial branch is to interpret and apply the laws and ensure their constitutionality.
The three branches of government share responsibility for the legal system. The Legislative branch (Congress) creates law; the Judicial branch determines their constitutionality and resolves disputes; and the Executive branch enforces the laws.
Trade spreads ideas and culture because it involves people moving from place to place around the world as they trade. As they move, they (and the people they meet) come into contact with new ideas and cultural practices
