Who defines powers of countries and cities?

The powers of countries and cities are primarily defined by their constitutions, laws, and legal frameworks, which establish the authority and responsibilities of various government entities. National governments typically delineate powers through constitutional provisions, while local governments derive their authority from state or national legislation. Additionally, international treaties and agreements can influence the powers of countries on a global scale. Ultimately, the balance of power can also be shaped by political processes, historical context, and societal values.