In Mellouli v. Lynch, the Supreme Court ruled in favor of Moones Mellouli, a lawful permanent resident who was facing deportation due to a drug paraphernalia conviction in Kansas. The case centered on whether his state conviction for concealing unnamed pills in his sock constituted grounds for removal under federal immigration law, which requires that any drug-related conviction involve a substance controlled under federal law. Although the Kansas statute covered nine substances not included in its federal counterpart, the government argued that it could presume Mr. Mellouli had been convicted of an offense relating to a federally controlled substance because most drugs are regulated at both levels. However, Justice Ginsburg delivered the opinion of 7-2 majority court rejecting this argument and holding that to trigger deportability, the government must connect an alien’s conviction directly with a federally controlled substance.

In the dissenting opinion for Mellouli v. Lynch, Justice Clarence Thomas argued that the majority's interpretation of immigration law was too narrow and failed to consider Congress' intent to make deportable any alien convicted of violating a law relating to controlled substances. He contended that Mellouli's conviction under Kansas law, which makes it illegal to use drug paraphernalia for any substance listed in its schedules (including those not covered by federal law), should be enough grounds for deportation as it relates directly with controlled substances. Furthermore, he criticized the majority’s reliance on a categorical approach comparing state and federal laws instead of focusing on specific conduct involved in each case.