D.C.’s Office of the State Superintendent of Education (OSSE) promised lots of outreach and transparency in its application for relief from portions of the federal No Child Left Behind Law. Evidently that doesn’t include the U.S. Department of Education’s response to the application, which OSSE has in hand but declines to release.

At least 18 of the 26 states seeking to opt out — including Maryland and Virginia— disclosed their letters, according to Education Week.

“We are in the deliberative process and all materials pertaining to the waiver will be released by [the Education Department] once it is approved,” OSSE spokesman Marc Caposino told my colleague Emma Brown in an e-mail last week.

“Deliberative process” refers to an exemption in the Freedom of Information Act that allows government agencies to withhold records that reflect a government agency’s “predecisional” deliberations and processes. There’s quite a bit of material that can be placed in such a category. Open government advocates say it is one of the most widely abused FOIA exemptions, a kind of safe harbor that protects revealing or embarrassing information from timely disclosure.

The Education Department is taking the same stance. Spokesman Daren Briscoe told Brown that the agency made a “categorical decision” to withhold the letters until final decisions were made on the waivers.

When Brown argued that the letters were public information, Briscoe said: “I’m not refusing to make it public but it’s a timing issue,” Briscoe said. “It will be made public at such time the process is complete.”

After a wobbly start, OSSE made good on what it called “robust stakeholder involvement.” There were focus groups, community meetings and requests for input on what to ask the U.S. Education Department, which has offered to waive some of the more vexing, one-size-fits-all aspects of the law. Many states, for example, want to get out from under the expectation of 100 percent proficiency on reading and math tests by 2014 and develop accountability plans the emphasize academic growth over annual test scores.

Eleven states have already received waivers. In its response to Virginia, the Education Department said the state’s achievement targets were not ambitious enough. It also said the plan to hold school systems accountable to performance of student subgroups was not strong enough. Maryland got generally high marks for its application.