On Tuesday, the American Civil Liberties Union (ACLU) petitioned the 9th US Circuit Court of Appeals to strike down a voter-approved Arizona law that denies bail to undocumented immigrants. According to the ACLU, the "no bail" law targets Latino immigrants who are being held in jail before they have been convicted of crimes.

"It's unfair to subject a certain subsection of the population to rules that don't apply to everyone else," said ACLU attorney Cecelia Wang, who argued that the law is unconstitutional, reports NBC News.

Arizona voters approved the law in 2006 as part of a series of measures aimed to crack down on illegal immigration in the state. The law denies bail to unauthorized workers who have been charged with certain felonies like aggravated identity theft, sexual assault or murder. It was proposed by former Republican Rep. Russell Pearce, who later introduced Arizona's infamous SB 1070, also known as "Show Me Your Papers" bill, in 2010.

State attorneys defended the law in the San Francisco federal appeals court, arguing that it was meant to improve public safety and prevent undocumented immigrants from fleeing the country before their court hearings. Arizona Assistant Attorney General Tim Casey also noted that Proposition 100 was approved by 78 percent of the voters and that is in the "compelling interest in keeping Arizona safe and undocumented workers out of the country," reports the Associated Press.

However, the ACLU contended that there is no empirical evidence showing that immigrants pose higher flight risks. As a result, Latino detainees are being unfairly held while other groups are allowed to put up bond before trial. They also argued that the state law is trumped by federal law.

One of the judges, Marsha Berzon, asked the rhetorical question, "How does one overturn the will of an overwhelming majority of voters to support the [federal] law?"

It could take months before the court rules, and the ACLU has the option of appealing an unfavorable ruling to the U.S. Supreme Court.

Arizona is not the only state with laws confronting the issue of bail for people in the country without authorization; Missouri and Virginia have similar laws.