After the Department of Justice appealed a federal judge's decision to appoint a special master to review certain classified files, the saga to track down and analyze the government documents that former President Donald Trump stashed at Mar-a-Lago took another turn.

Trump's case and the appointment of a special master made national security experts worried.

Three former judges and a former counsel to the Governor of Florida are on the proposed candidates list.

The special master would need to have the highest national security clearance in the US in order to be appointed.

The universe of people who have high-level clearances, but also have expertise in areas of executive privilege and attorney-client privilege is small, according to Larry Pfeiffer, a national security expert.

There are more questions about how the probe will play out after the appointment of the special master. The experts broke it down.

How are special masters usually used?

In court cases where there is a need to review attorney-client privilege, a special master is usually hired to investigate.

In cases where a settlement is needed to be doled out in a class action lawsuit, special masters are used.

What a special master could do in the DOJ's case

Time is the biggest impact of requesting and appointing a master.

Because of the sensitivity of the documents, whoever they choose is either going to have to already have the clearance at that level, or they're going to have to go through the process.

The goal of the special master's review is to determine if any of the documents are protected by attorney-client privilege.

Both parties indicated on Friday that they would want to review the report before it was presented to the judge.

The DOJ and Trump's team disagree on whether a special master should be allowed to review the classified documents.

Pfeiffer told Insider that if the nominee is required to review classified documents, they would need the highest level of national security clearance.

Who foots the bill for the special master? 

Parties usually split the cost of hiring a special master, although that decision is up to the judge.

On Friday, Trump's team asked the parties to split the costs, while prosecutors wanted the former president to pay the majority of the expenses.

What's behind Trump's claims of executive privilege

The DOJ's actions are political, according to Trump. The documents from Mar-a-Lago could be protected by attorney-client or executive privilege.

The Dean of the Schar School of Policy and Government at George Mason University told Insider that Trump's team most likely will try to claim executive privilege over any documents that they believe would compromise confidential White House communications. Donald Trump's claim to a continuing need for secrecy is difficult to prove, as executive privilege protects the right of the president to receive candid advice without fear of disclosure.

After Trump asked the National Security Counselors if he was a good candidate to be Special Master, he declined the nomination.

The Espionage Act is the focus of the investigation by the DOJ.

The selection process itself could impact intelligence relationships

Pfeiffer said that the quest to find a special master could take months and that the probe could be delayed. Since the department can't be sure about the location of their materials and who they may have been shared with, certain intelligence relationships may suffer.

Pfeiffer said that he had never seen a breakdown in the flow of classified documents in his time at the White House.

I was familiar with the paper flow inside the White House. Pfeiffer said that records need to be tracked and kept in a lot of large organizations. Something went wrong with a bunch of people who are permanently employed by the White House. Either they were intimidated by the Trump White House or there was a lot of abuse of the system.