The United Nations (UN) offers a wide variety of work for lawyers in many different countries. This can include legal advisors for the UN in Geneva or New York; advising governments on judicial reform; training and advising judiciaries on legal issues, long-term education and legislative reform; advising on the implementation of legal aid structures; working in conflict environments; courtroom prosecutions of human rights violations etc.
The UN Human Resources website (see below) lists international job vacancies under 'occupational groups' - 'legal affairs'. Applications can be submitted online. Salaries for professional staff are set by reference to the highest-paying national civil service - that being the USA.