A well-functioning system of checks and balances and civil liberty guarantees give the United States "high marks," the non-profit World Justice Project said in its 2011Rule of Law Index.
But the civil justice system is often unobtainable by "disadvantaged people," the report said.
"Legal assistance is expensive or unavailable [ranking 52nd out of 65 countries surveyed], and the gap between rich and poor individuals in terms of both actual use of and satisfaction with the civil courts system remains significant," the report said.
"In addition, there is a general perception that ethnic minorities and foreigners receive unequal treatment from the police and the courts," the report said.
People in Argentina "have better access to legal counsel in civil disputes" than do people in the United States, the report said.
Sweden and Norway lead the world in most rule-of-law categories, with the Netherlands and Germany following closely behind and the United States and Canada trailing further. Italy is the weakest performer in the North American-European region.
Poland and the Czech Republic stand out among former centrally planned economies, while Russia ranks low in most categories, the report said.
Russia also ranks at the bottom among the so-called BRIC countries of Brazil, Russia, India and China, deemed at a similar stage of economic development.
Latin American and Caribbean countries have moved toward openness and political freedom, but the region's public institutions "remain fragile," the report said. Latin American corruption and a lack of government accountability are still prevalent, and the region shows the highest crime rates in the world.
Chile leads Latin America in all categories, followed by Brazil. Mexico trails far behind.
Middle Eastern and North African countries fall into the middle of the global rankings in most rule-of-law categories. Crime is low, but governments show "serious weaknesses in the areas of accountability, checks and balances, openness and respect for fundamental rights," the report said.
South Africa and Ghana lead the Sub-Saharan region, which generally scores lower than other areas of the world.
Japan is one of the highest-ranking countries in the East Asia and Pacific region, the report said. Corruption in Indonesia is pervasive, ranking second-to-last in the region and 47th globally.
The World Justice Project defines the rule of law using universal principles. Its goal is to strengthening the law's power to "uplift, protect and create opportunity," the organization said.