The justices ruled that police can stop, question and detain anyone they suspect of being in the country illegally.
The justices ruled that states may not make it a state crime for people to be in the U.S. illegally or for illegal immigrants to seek work in their state.
Another key provision of the Georgia and Arizona laws was left untouched by Monday's ruling. Both states require businesses and government agencies to use the online E-Verify system to determine the immigration status of new hires.