House Oversight Committee Chairman James Comer (R-KY) announced Friday that the committee has launched an investigation into former President Joe Biden’s use of an autopen to authorize a series of controversial last-minute pardons.

“So our newest investigation at [the] Oversight Committee is we’re investigating the autopen, and I think we’ve identified the staffer” who was using it, the chairman said during a speech at the Republican National Lawyers Association’s policy conference in Washington, according to the Washington Examiner.

The committee’s investigation focuses on whether President Biden, whose cognitive health was reportedly deteriorating in his final months in office, was mentally capable of authorizing the use of the autopen for official documents, or if senior aides issued the pardons without his direct involvement.

“If what we think is going to play out on the autopen [investigation], it’s going to create a strong case on the pardons,” Comer said.

While the autopen has been used by presidents for decades, most notably by President Barack Obama in 2011 to extend the Patriot Act, its use for issuing pardons has never been tested in court. A 2005 Justice Department opinion stated that a president may authorize someone else to sign on their behalf. However, a federal appeals court ruled last year that a pardon does not even require a written document to be legally valid, the Examiner reported.

Legal experts indicate that certain elements of the recent pardons, particularly President Biden’s blanket pardon for his son, Hunter Biden, may pose constitutional questions.