In the first week of May—without comment or, apparently, any concern for its impact—U.S. immigration officials unilaterally rewrote the law, disqualifying thousands of families and workers trapped half-way through the green card process. As a result, people who just last month would have been welcomed as legal residents are now facing deportation, most with no hope of return.

It’s not clear what prompted this policy, but the draconian new interpretation wasn’t needed to implement or comply with new law. And given the administration’s stated goals of promoting both change and transparency, this mean-spirited end run by an agency that lacks even a sitting Director, is puzzling at best.

In our current “zero-tolerance” climate, even the most minor immigration violation often prevents a person from obtaining legal status. Since 1996 (and before), our immigration laws have provided severe penalties for overstaying a visa, working without proper documents or remaining in the country unlawfully. At the same time, however, Congress also provided a limited—and critical exception: those with established family ties or employment–people with no criminal history, no record pf serious immigration violations or security concerns–might nonetheless complete the process after paying a whopping $1000 fine, beyond the usual hefty fees and expenses.Even with these harsh restrictions, for those that complied with the law, there was at least the prospect that families could be reunited and needed workers successfully become residents.

But that all changed when USCIS—the agency tasked with adjudicating immigration benefits—decided to ignore more than a decade of precedent (including two circuit courts of appeals decisions).Now, the agency will not only refuse to accept any applications filed under this provision, but will deny—and seek to deport–those who relied on the law.

These immigrants weren’t taking advantage of a loophole or cutting ahead of the thousands who are trapped in our unworkable immigration system:on the contrary, they stood in line and paid thousands in extra fines and fees; and many have been waiting more than a decade for their chance at citizenship.

This decision doesn’t just impact intending immigrants, but also their families, employers and the communities in which they have legally resided all these years.We insist that would-be immigrants play by the rules, but what happens when USCIS changes the rules in the middle of the game? We all lose.

Editor’s Note: The policy change referenced here relates to a May 6, 2009 USCIS memo on Consolidated Guidance Concerning Unlawful Presence.