From the ACLU press release at commondreams.org/newswire/2009/07/15-4

The American Civil Liberties Union filed a Freedom of Information Act request Tuesday for new documents governing the continued delegation to state and local law enforcement agencies of federal immigration enforcement authority. The fundamentally flawed program has been associated with serious civil rights abuses and public safety concerns...

[references the DHS changing their rules]

"No amount of tinkering with the 287(g) program is likely to solve the fact that it threatens public safety and undermines the basic guarantee of equal treatment by increasing profiling of people who look or sound ‘foreign,'" said Omar Jadwat, staff attorney with the ACLU Immigrants' Rights Project. "Still, DHS's refusal to disclose these new documents is a disappointing and legally unsupportable step back from with Bush administration practice and makes it impossible to fully evaluate the changes to this highly controversial program. DHS should immediately release the documents we have requested."

The ACLU has long sought to end the 287(g) agreements between DHS and state or local agencies that are, by design, fundamentally flawed. The 287(g) agreements have encouraged illegal racial profiling and civil rights abuses as well as the mistaken and unlawful detention and deportation of U.S. citizens and permanent residents, as reflected in a series of lawsuits, all while diverting scarce resources from traditional local law enforcement functions...

Like the ACLU cares about any form of law enforcement. Their goal with this and the other steps they take is to make illegal immigration easier; they even collaborated with the Mexican government to further that goal. And, this is a preview of how they'd act if the comprehensive immigration reform they support passes. CIR is sold in part by many as having tough enforcement; if it passes, the ACLU would begin to weaken that enforcement through actions like the above. Note also that the press release quotes Joanne Lin giving a flawed analogy.