Everything you need to know about Carter Page, FISA and Donald Trump

(CNN)On Sunday night, I came across a terrifically informative Twitter thread from April Doss regarding this weekend's release of a previously classified foreign surveillance warrant application on one-time Trump campaign official Carter Page. The warrant, approved in 2016, allowed the FBI to conduct surveillance on Page.

President Donald Trump had already seized on the contents of the release as evidence that the entire special counsel investigation into Russian election meddling was a hoax and a witch hunt. Others insisted the FISA warrant showed the process working exactly as it should.
I reached out to Doss to walk me through the FISA process and shed some light on who is right when it comes to the Page warrant in particular. She knows of what she speaks: She spent May 2016 to May 2017 as the senior minority counsel for the Senate Intelligence Committee's Russia investigation and is now the chair of cyber & privacy at the law firm Saul Ewing. She has also previously served as the head of intelligence law at the National Security Agency.
Our conversation, conducted via email and lightly edited for flow, is below.
    Cillizza: Let's start simple. Explain the FISA court and how FISA warrants are obtained.
    Doss: The FISA process goes back to the late 1970s. During the 1970s, in the post-Watergate era, Congress and the American public were concerned that the US government was spying on Americans, particularly on progressive causes like the civil rights movement and anti-Vietnam War protesters.
    After a series of public hearings in Congress -- known as the Church and Pike Committees -- a number of reforms were put in place that would restrict the government's ability to spy on people in the US, and created stricter oversight mechanisms across all three branches of government to ensure that, if the intelligence or law enforcement agencies (CIA, FBI and the like) believed they needed to collect information on specific Americans for intelligence or counterintelligence purposes, the agencies would have to meet very clear standards explaining why they suspected that person was a counterintelligence threat, what information they sought to collect about the person, and how the information would be protected.
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    The Foreign Intelligence Surveillance Act was a key part of those reforms. Passed in 1978, it created a framework for federal judges to oversee any requests by the government to use electronic surveillance -- wiretapping -- to spy on Americans, and it created a structure of congressional oversight of the executive branch's wiretap requests and transparency for Congress into the decisions by the FISA court. The FISA legislation has complex definitions about what constitutes "electronic surveillance," what it means to be an "agent of a foreign power," and what the process is for approving electronic surveillance in different circumstances.
    The law establishes the Foreign Intelligence Surveillance Court (FISC) and creates a set of procedures for federal judges to review the government's requests for surveillance approval under FISA. All 11 of the judges on the FISC are appointed by the chief justice of the Supreme Court. They're all sitting federal judges who are busy with a full docket of cases in their home districts around the country, and they all travel to the FISC courthouse in Washington, DC on a rotating schedule in order to review FISA applications, hear arguments from the government, address any compliance issues that have arisen from FISA matters and issue orders.
    Although the judges aren't in Washington full time, the FISC is staffed by fully cleared personnel, including staff attorneys who review all of the applications and can make recommendations to the judge about whether there are novel issues in the application, whether the government should be required to submit additional information, whether a particular application can be decided on the pleadings -- the paperwork -- or should have a hearing where the judge can ask the government questions about the application (including evidence in it), etc. Under the FISA court rules, the judge can direct the government to provide any additional information that the court thinks is necessary in order for it to make a decision.
    Finally, it helps to remember which part of the FISA statute we're talking about here. In 2017, there was a great deal of debate over the reauthorization of a different section of FISA, section 702, that deals with collecting communications of non-US persons outside the United States. The documents released on Saturday, however, have nothing to do with section 702. This was an application under Title I of FISA, alleging that a US citizen inside the United States was acting as an agent of a foreign power.
    Cillizza: How hard is it to get a FISA warrant? And what about getting it re-upped?
    Doss: Getting approval on a Title I FISA application takes a lot of work -- as it should, since an approval allows wiretapping US persons. You can see how much detail and effort goes into these applications just from looking at the documents themselves: the initial application on Carter Page was almost 70 pages long, and -- although some of the information is redacted -- you can see that it includes background information on Russian intelligence operations generally and Russian attempts to influence US elections, as well as the concerns the FBI had about the activities of the particular subject in this application, Mr. Page.
    This is much more than just a paperwork drill. All FISA applications go through a lengthy process of approvals within the executive branch as well as in front of the FISC. The details of the process vary according to which section of the FISA legislation is being used to support the application. But the key points for any Title I FISA application are that they go through lengthy internal vetting at the originating agency -- in this case at the FBI. That vetting includes a lot of career FBI agents and lawyers and a supervisory special agent before it gets to the level of the FBI director or deputy director for approval. The same thing happens at the Department of Justice, where working-level career attorneys in the National Security Division review the application before it goes to the head of NSD for approval and then to the attorney general or deputy attorney general.