Immigration groups and civil-rights advocates generally applauded the administration's decision to release more than 2,000 immigrants from detention. But they argue that U.S. Immigration and Customs Enforcement should have done this long ago — and are now pushing the administration to become much more committed to using alternatives to detention for immigrants charged with potential deportation.

(Source: AP) (Source: AP)

The ACLU lays out its case in a new statement submitted for an upcoming House Appropriations hearing on ICE's rationale for the mass release. "ICE’s stated justification for the releases—that it had determined these individuals could be 'placed on an appropriate, more cost-effective form of supervised release'raises a fundamental question, posed among others by Secretary Janet Napolitano herself: why were these individuals detained in the first place?" the ACLU writes in the statement for the hearing, which is scheduled for Thursday morning.

Citing figures derived from a Freedom of Information Act Request, the ACLU claims that 35 percent to 55 percent of detainees aren't required by law to be in immigrant detention; rather, they "generally have no criminal records and are being detained solely on the basis of flight risk" at the agency's discretion. The statement goes on to cite anecdotal stories about some of the detainees who were recently released, including a domestic violence survivor with four children who are U.S. citizens, who was detained for 19 months "based on two misdemeanors from five years ago," according to the statement.

The ACLU believes that one of the reasons that such immigrants are being detained is because ICE is mandated by Congress to maintain 34,000 detention beds on a daily basis. (ICE has denied that it has set numerical deportation quotas to fill.) To that end, the civil-rights group wants Congress to "eliminate language requiring a specific number of detention beds to be maintained or filled" and give ICE more support and funding for alternatives to detention that would track immigrants facing detention through other forms of monitoring.

Many Republicans, however, are concerned that ICE is not doing enough to fill immigrant detention beds—and accuse the administration of using bad policy to play politics with the mass release of detained immigrants last month. "Congress mandated and provided resources to maintain 34,000 bed spaces for illegal immigrant detainees. As of last week, ICE reported 30,773 spaces filled, in clear violation of statute," wrote House Homeland Security chair Rep. Michael McCaul, in a letter to ICE director John Morton.

The whole issue has been muddled by the lack of clarity from ICE  about the rationale for the mass detainee release, with contradictory statements about whether or not it was sequester-related. Thursday's hearing should start to clear up some of those questions, so the debate can proceed in earnest.