As he walked down a Brooklyn block with a loaded gun in his hand on a dry, hot summer evening in 2016, Javier Perez didn't know he was about to trigger a constitutional dilemma.

Seeing a group of youths assaulting a boy from a rival gang with bats and machetes, Perez did what he thought could defuse the situation: He fired a few shots in the air. The brawlers dispersed. No one was injured. Perez walked back to a barbecue he was attending with a few old friends on the same block, returning the gun he had just borrowed to one of them.

Months later, Perez was arrested and charged with a federal crime — being an "alien in possession of a firearm." He faced 10 years in federal prison and deportation.

His lawyers argued the federal law is unconstitutional because it strips people like Perez — millions of undocumented people with no prior criminal record — of Second Amendment rights. The government shot back that the amendment doesn't apply to Perez because of his unlawful status in the country, and even if it did, the law is reasonable in achieving a government's interest in controlling crime.

After failing in the lower courts, the case now has the potential of ending in the U.S. Supreme Court, where it could have far-reaching implications for immigrant rights beyond gun possession, legal experts say.

Does the Second Amendment Cover Immigrants?

Both parties in the Perez case based their arguments on the seminal 2008 Supreme Court decision in District of Columbia v. Heller, in which the high court said for the first time that law-abiding individuals had a right to possess firearms for self-defense in their homes.

The court said that right was not absolute, and convicted felons and the mentally ill should be barred from possessing guns. But it didn't say anything about immigrants. .....