(NewsNation) — President Joe Biden’s defense of his mental acuity has again raised the issue of competency in the White House, which spotlights a constitutional amendment covering the Commander-In-Chief’s ability to serve.

Section 4 of the 25th Amendment outlines the transfer of power should the president became unable to discharge the powers and duties of his office. The Brookings Institute believes the amendment, however “opens up a gray area” as to whether the wording could become grounds for removing a president for a lack of competency.

The 25th Amendment was ratified in 1967 following the assassination of President John F. Kennedy. It addresses the transfer of power should a sitting president die, resign, or becomes incapacitated.

However, the amendment has only been used when a president became physically incapacitated, including the assassination attempt on Ronald Reagan in 1981 and twice by President George W. Bush when he was sedated to undergo a colonoscopy, according to the Brookings report.

Biden mostly dodged questions from reporters Thursday night whether he should continue as president or seek a second White House term. The questions arose after DOJ special counsel Robert Hur characterized Biden as a “well-meaning, elderly man with a bad memory” in his report on Biden’s handling of classified documents.

Hur’s investigative report claimed Biden could not remember when he served as Vice President under President Barack Obama or when his son Beau died.

According to the 25th Amendment, the vice president and a majority of the “principal officers” of the executive branch or members of Congress would submit a written declaration that the president is unable to discharge the powers and duties of the office.

The amendment calls for the Vice President to assume the office of acting president should the president be found to be unfit either physically or mentally.

Former president and presumptive Republican presidential nominee Donald Trump told NBC’s “Meet the Press” in September that he is in favor of a sitting president undergoing a competency test despite some claiming it is “unconstitutional.”

Trump, who has called Biden “incompetent” in past interviews, underwent a 15-minute competency test, the Montreal Cognitive Exam, while in the White House. In the NBC interview, Trump boasted that he “aced” the test and “got every question right.”

Biden on Thursday defended himself by saying, “I know what the hell I’m doing” and characterized himself as the most qualified person in the United States to serve as president.