Editor’s Note: This is the second of five blogs in a series focusing on firsthand experiences with Secure Communities from across the country.

Detain first, investigate later — that is Immigration and Customs Enforcement’s (ICE) mantra when it comes to its Secure Communities (“S-Comm”) program, a program designed to immediately ensnare any immigrant in the deportation pipeline the moment they come into contact with the criminal justice system.

Under S-Comm, the fingerprints of every person arrested by the police are shared with ICE at the moment they are booked into police custody. Without investigating the person’s immigration status, ICE immediately sends an “immigration detainer” or a request back to the police if they want the person to continue to be detained for immigration purposes. Detain first, investigate later.

See a problem with this? Not only does it violate the Fourth Amendment’s basic prohibition against detaining a person without probable cause to do so, but it commonly ensnares the wrong people, including people who are not even immigrants, but United States citizens, causing them to be unlawfully detained.

Take, for example, the case of Antonio Montejano, a U.S. citizen who was born in Los Angeles. A few weeks ago, Antonio was arrested by the Santa Monica Police Department for shoplifting. He accidentally left a Sears store without paying for the candy his young children had taken and eaten while in the store. One of his children also placed a $10 perfume bottle in a bag that had already been paid for.

When security guards stopped Antonio, accusing him of stealing the perfume, Antonio explained that it was an honest mistake and that he would be happy to pay for it. After a long back and forth with the security guards, the police were called and Antonio was taken into custody.

Antonio normally would have been released from Santa Monica Police custody within hours of being booked into their custody. But ICE interfered through S-Comm. When Antonio was booked, ICE immediately placed an “immigration detainer” on him, instructing the local authorities to detain him until they could pick him up.

Antonio spent four haunting and unwarranted days in jail on the immigration detainer. For two of those days, Antonio was detained in a temporary holding cell in Los Angeles County Sheriff’s custody that only had chairs, no beds. The authorities forced him to sleep on the hard floor, depriving him of any mattress or blankets, a practice the federal courts have long denounced as flagrantly unconstitutional. Antonio repeatedly protested to jail authorities that he was a U.S. citizen. But only after the ACLU of Southern California contacted a senior ICE official four days later, did they finally agree to lift the detainer.

Romy Campos, a 19-year-old U.S. citizen born in Florida and a dual citizen with Spain, had a nearly identical experience, also a few weeks ago. Her arrest at a mall in Torrance, Calif., also resulted in ICE placing an immigration detainer on her and detaining her for four days in jail. For days, her attorney and family members sent her birth certificate to ICE officials pleading that they lift the erroneous detainer to no avail. Again, the detainer was only lifted once the ACLU of Southern California contacted a senior ICE official.

ICE, quite clearly, has no business arresting and detaining American citizens. But as described in a recent report by the Warren Institute at University of California — Berkeley, they do so over and over again through the fundamentally-flawed S-Comm program. (ICE’s own data in the first year of S-Comm activation revealed that five percent of persons identified by S-Comm were in fact U.S. citizens.) And they do so by enlisting the unwitting participation of local jail authorities in these unconstitutional practices.

The costs and consequences of S-Comm’s detain first, investigate later are borne out every day in the jails and police stations across the country where non-deportable citizens and noncitizens suffer needless detention, while they beg for ICE to finally investigate their cases so that they may be released from jail.