Final answer:
Detaining and questioning an individual solely based on surname or accent for immigration violations is not permissible under the Foreign Nationals directive and constitutional protections. The Supreme Court has underscored the federal authority over immigration and warned against using racial profiling in such laws.
Step-by-step explanation:
Under the directive outlined by the Foreign Nationals related to probable cause for questioning an individual's immigration status, actions solely based on a person's surname or accent would not be permissible. Probable cause must be based on facts and circumstances that would lead a reasonable person to believe that a crime may have been committed. In the United States, constitutional protections against unreasonable searches and seizures, as well as against racial profiling and discrimination, would preclude an officer from detaining and questioning an individual solely based on their surname, which corresponds to racial or ethnic background.
The Supreme Court case Arizona v. United States reaffirmed the federal government's authority over immigration policy and cautioned against racial profiling, indicating that states could face civil rights lawsuits if such laws were applied based on racial bias. Furthermore, the 'show me your papers' provision upheld by the Supreme Court allows officers to check immigration status only during a lawful stop, detention, or arrest, still requiring reasonable suspicion that is not based exclusively on race or ethnicity.