> The ACLU said that its recent Freedom of Information Act request to better understand the system has been ignored. Now it’s suing to ask a judge to turn over the documents.

I'm not certain, but it seems like the government ignoring FOIA requests has been an ongoing problem for years. I'm reading FOIA.gov right now, and don't see anything yet, but are there any explicit deadlines for a reply or automatic penalties for dropping requests on the floor instead of replying? Are there good reasons why some requests should be ignored, as opposed to, say, citing an exemption?