The law requires federal agencies to respond to FOIA requests within 20 days, and this may be extended to 30 days under unusual circumstances. The USCIS says that it responds to FOIA requests on a first-in first-out basis. It gets about 100,000 FOIA requests annually and has reduced the backlog within the last five years. However, delays still do exist.
Immigration judges frequently deny requests to delay deportation proceedings for people who are waiting for documents from a FOIA request. In some cases, a court may compel the federal agencies to provide documents when there is a delay.
For a court to move forward with deportation proceedings while the subject of those proceedings is helplessly waiting for documents that may be critical to a defense would seem to violate that person’s right to due process under the Constitution. What makes this appear especially unfair is that the government can pursue a person’s deportation, while at the same time denying that person access to possible exculpatory evidence.