Democrats in Congress are once again calling for Jared Kushner’s top-secret security clearance to be revoked in the wake of revelations that Kushner attended a meeting with a Russian lawyer promising dirt on Hillary Clinton during the presidential campaign — a meeting he initially failed to disclose on his security clearance application.

They argue that the president’s son-in-law and top adviser, who has been identified as a “person of interest” in the FBI investigation into Trump’s Russia ties, shouldn’t have access to classified information, especially if he intentionally left off his foreign contacts when he applied for his clearance.

That’s in part because security clearances are meant to be a judgment of a person’s “character and trustworthiness,” a Congressional Research Service report on the clearance process explains.

ADAM SCHIFF: Jared Kushner security clearance should be reviewed and then revoked if review shows he wasn't candid — Kasie Hunt (@kasie) July 14, 2017

But while the 4.2 million Americans who’ve done work for the federal government or a government contractor have experienced the byzantine and often tedious process of obtaining a security clearance, most Americans are probably unfamiliar with how it all works.

So here are some clear answers to the top questions about what a security clearance means, how a person goes about getting one, how and when they can be revoked, and — crucially — what revoking Kushner’s security clearance would actually mean for his ability to access classified information.

What is a security clearance?

A security clearance determines whether an individual is eligible to access classified national security information. That’s any information that, if disclosed, could potentially damage US national defense or foreign relations. Any federal employee or contractor must be granted a security clearance before working with classified information.

There are three levels of security clearances corresponding to sensitivity of information the individual needs to access for their job: confidential, secret, and top secret. Most White House jobs require top-secret clearance.

“For someone relatively senior in the White House, they’re going to have access to the classified information if the president says it’s required,” Evan Lesser, the founder and president of ClearanceJobs.com, a website providing information about security clearances and defense jobs, told me in an interview.

Having a security clearance doesn’t mean you automatically get access to all the information classified at that level, though. Classified information is typically shared on a “need to know” basis — which means that a lot of sensitive intelligence is off limits unless someone specifically decides you need to be read in on it.

How do you get a security clearance?

Even though Jared Kushner is the president’s senior adviser (and son-in-law), the process he had to go through to obtain his security clearance essentially would have been the same for him as for any other government employee.

“In general, a senior White House official should technically be going through the same process as some guy fixing the air conditioning in a government facility in the desert,” said Lesser. The only difference depends on the level of security clearance desired.

The first phase of the process is agency sponsorship. An individual can’t just apply to get a clearance on their own; rather, they must be sponsored by the federal agency that wants to hire or work with them.

During this phase, the person applying for the security clearance submits the necessary paperwork. This includes submitting a 127-page form, known as the SF-86, detailing all “close and/or continuing contact with a foreign national within the last seven years,” as well as lots of other information about their extended family, where they’ve lived in the past, and all previous employment.

The SF-86 is the form on which Kushner initially failed to report his contacts with foreign nationals.

After that, the process moves into the investigative phase. An investigative agency looks into all the claims made on the SF-86 form, interviews relatives and neighbors, and verifies that all information provided by the candidate is accurate.

For most federal employees, the investigation is conducted by the National Background Investigations Bureau, which provides more than 95 percent of the government’s background investigations. But for senior White House and Cabinet-level officials, the investigation is generally conducted by the FBI.

The final phase is adjudication, where it’s determined whether the individual should be granted the security clearance. Usually that involves the investigations bureau sharing its findings with the sponsoring agency that requested the security clearance for the individual in the first place. Then the sponsoring agency gets to decide whether to grant or deny the security clearance.

What are investigators looking for specifically?

The investigative phase is the most rigorous and time-intensive part of the process. For individuals requesting a top-secret security clearance, this could take more than 400 days. Lower security clearance levels could take around 200 days.

For some government positions, an individual could be granted an interim security clearance that would quickly give them access to some sensitive information and enable them to do their job. This seems to be the case for Kushner, as the New York Times reported in April that he had interim security clearance. In other cases, the person might have to wait for the security clearance to be granted to start working.

Andrew McCanse Wright, an associate professor at Savannah Law School and a founding editor at the national security law analysis website Just Security, has been through the security clearance process five times — most recently when he served as associate counsel to President Obama in the White House Counsel’s Office. He explained to me what investigators are looking for.

“They're testing a lot of different things, but mostly it's designed to get a sense of your veracity, whether you're truthful with them, and whether or not there's areas of vulnerability that could lead to exploitation by a foreign power,” he said.

Investigators are trying to determine the likelihood that the individual could leak sensitive information to the public or to a foreign government and whether the individual might be susceptible to blackmail, and to get a good understanding of the person’s overall character.

There are 13 specific guidelines that investigators look into — including allegiance to the US, foreign influence, and financial background — and they all carry the same weight. Investigators follow the “whole person” concept, meaning they look at all the information together and determine whether the person is acceptable.

In the case of Kushner, there are two categories investigators are likely to focus on given media reports about Kushner’s apparent meetings with Russians: foreign influence and foreign preference.

Foreign influence encompasses living with a foreign national, having a family member or friend who is a foreign national, doing business with a foreign national, and traveling abroad.

Foreign preference has to do with loyalty to the United States. That includes accepting some kind of benefit from a foreign country, voting in another country’s elections, working in another country’s government or military, and holding a passport other than one from the US.

The top reason someone might be denied a clearance is because of their financial issues, including having substantial debt or filing for bankruptcy, according to a report ClearanceJobs published this year. The second most common reasons people are rejected is personal conduct, which is often when a person lies or falsifies information on the SF-86. Foreign influence is the fourth most common cause of clearance denial.

What happens if you lie or omit information during the investigation process?

According to Lesser from ClearanceJobs, intentionally omitting information from the SF-86 form is actually a federal crime. An individual could be put in jail for purposely failing to disclose information.

But there are certain situations and arguments that could mitigate that. If the person was truly unaware that they should’ve included an interaction on the form — for instance, if the interaction was very minor — then that could be mitigated.

It’s really a case-by-case basis and depends on what the issue is when determining if the person has committed a federal crime.

How is a security clearance revoked?

People who are granted security clearances are periodically reinvestigated to determine if they are still qualified. For example, individuals with top-secret security clearance (which is what Kushner applied for) are investigated at least once every five years.

If there is evidence that the individual has violated any of those 13 categories used to investigate the person when they initially applied for clearance, including foreign influence, then the security clearance could be revoked.

Security clearances can be, and occasionally are, revoked. Around 1 percent of people who apply for security clearances are either denied or have their clearance revoked later on, according to a report of data compiled by ClearanceJobs in 2010. But the actual number is misleading, said the report’s author, William Henderson, because the majority of individuals with serious issues opt out of the process themselves.

When it comes to the White House, it’s unclear who makes the final decision about whether to revoke the clearance, but in most general cases it comes back to the final adjudicator who granted the clearance in the first place.

“Presumably this adjudication process is fairly routinized and is not a political decision,” said Wright. “It's an assessment of potential threat vulnerability to the American people.”

If Kushner’s security clearance were revoked, would it matter?

If we entertain the hypothetical situation in which Kushner’s security clearance is revoked, an interesting question arises of whether President Trump would stop giving Kushner access to top-secret information.

The president has a lot of power over security clearances, including the authority to pass executive orders on security clearance policy and to establish the standards related to access of classified information. For example, in 2016 President Obama passed an executive order that amended the structure and processes for issuing security clearances.

What’s more, the president can decide unilaterally to declassify any classified information he wants if he feels it’s warranted.

So if Trump decided that he wanted Kushner to continue receiving classified information, even if Kushner’s clearance was revoked, he could find a way to make that happen.

“I don’t think a garden-variety civil servant, a government official who wasn't the son-in-law of the president, would continue to have access to classified materials with these kinds of stories coming out in the press,” Just Security’s Wright said.

Lesser agreed: “I assume there would be a fair amount of uproar considering the process is fairly set in stone. Ninety-nine percent of people with clearances go through the same process and have the same guidelines, but the White House is a very different situation.”

“Technically, just about anything could happen,” said Lesser. “It really hasn’t in the past, but it could.”