Contempt of congress

There is a conservative group called, Judicial Watch” that uses the freedom of information act (FOYA) and they consistently get information that congress asks for but doesn’t get. Congress is supposed to have oversight responsibility on the executive branch but even issuing subpoenas and charging them with contempt does not get them the info. The House has voted to hold Attorney General Eric Holder in contempt of Congress over his failure to turn over documents related to the Fast and Furious scandal, the first time Congress has taken such a dramatic move against a sitting Cabinet official. This was not just politics since The vote was 255-67, with 17 Democrats voting in support of a criminal contempt resolution, which authorizes Republicans leaders to seek criminal charges against Holder. The problem is that the Justice Department is responsible for prosecution and "across administrations of both political parties, the longstanding position of the Department of Justice has been and remains that we will not prosecute" So it appears that not only can congress not get requested information but when they don’t there is not much they can do about it. So much for oversight.