In the United States v. Padilla case of 1992, the Supreme Court examined whether a defendant's Sixth Amendment right to counsel was violated when their attorney failed to advise them about potential deportation consequences following a guilty plea. The defendant, Jose Padilla, an immigrant from Honduras who had been living legally in the U.S for over 40 years, pleaded guilty to drug charges on his lawyer’s advice but claimed he was not informed that this could lead to his deportation. The court ruled that defense attorneys must inform clients if pleading guilty carries a risk of deportation because it is part and parcel of ensuring they make fully informed decisions regarding their cases. This decision expanded defendants' rights during plea negotiations and underscored how important competent legal representation can be for non-citizen defendants facing criminal charges.

In the dissenting opinion for United States v. Padilla, Justice Blackmun argued that the majority's decision to allow evidence obtained through a warrantless search of a vehicle was inconsistent with previous Supreme Court rulings on Fourth Amendment rights. He contended that there were no exigent circumstances justifying such an intrusion and thus, the police should have obtained a warrant before conducting their search. Furthermore, he disagreed with the majority's view that an individual has less expectation of privacy in his or her automobile than in his or her home or office. According to him, this distinction is arbitrary and not supported by precedent cases nor constitutional principles. Therefore, he believed that allowing such searches without warrants undermines citizens' protections against unreasonable searches and seizures as provided by the Fourth Amendment.