Seeing as you don't bother to read with comprehension:
A military security clearance is an official determination allowing an individual to access classified national security information. Obtaining one is a prerequisite for many military roles, enabling personnel to handle protected information.
A security clearance is considered a privilege, not an inherent right. It is granted based on a thorough assessment of an individual’s character, conduct, and loyalty. The Department of Defense manages these investigations to ensure that those entrusted with classified information meet stringent eligibility requirements.
Obtaining a military security clearance begins with the applicant completing a detailed questionnaire, such as the Standard Form (SF-86), often submitted electronically through systems like eApp. This form requires a comprehensive history, including residences, employment, educational background, and any foreign contacts over the past ten years. Applicants must also disclose financial records, criminal history, and any past drug or alcohol use. Omissions or inaccuracies can lead to denial.
Following the submission of the questionnaire, a comprehensive background investigation is conducted to verify the provided information and assess the applicant’s trustworthiness. Investigators perform checks of national records, credit history, and criminal records. They also conduct interviews with individuals who know the applicant, such as friends, family, and former employers, to gather insights into their character and reliability. This investigative phase aims to identify any potential vulnerabilities or risks.
Once the investigation is complete, the gathered information undergoes adjudication. This involves a review of all findings against specific adjudicative guidelines to determine eligibility for a security clearance. Factors considered include allegiance to the United States, personal conduct, financial responsibility, and any foreign influence. The Department of Defence Central Adjudication Facility (DoD CAF) makes the final decision on whether to grant or deny the clearance.
A practical look at how military security clearances work — from the SF-86 and background investigation to what can get your clearance denied or revoked.
legalclarity.org
The reference you gave is for a person on trial where classified information is relevant.
This is not the case with people who have not been charged and are consulting an attorney before writing a book or making a documentary. In that case, no attorney will be allowed access to classified information and divulging such information, even verbally, is a criminal act.
Now stop pitter pattering around the subject. There are several on this forum who have held or hold security clearances of various grades and know the rules.