President Donald Trump has been butting heads with NFL players due to the #TakeAKnee national anthem protest, but it looks like the leader of the movement, Colin Kaepernick, may be about to raise the stakes. 

According to Yahoo Sports, the former NFL player's legal team plans to seek federal subpoenas demanding Trump's testimony concerning Kaep's ongoing collusion case against the NFL. Along with Trump's testimony, Kaepernick's lawyers also plan to subpoena Vice President Mike Pence and other officials familiar with Trump's NFL protest agenda. 

Kaep's lawyers want to find out how much the executive branch influenced team owners' stance on the anthem protests during the quarterback's free agency. Trump spoke directly to many team owners about the protests; Kaepernick's legal team hopes to discover just what the president told them.

It isn't clear whether Trump, as a sitting president, can be subpoenaed. Naturally, Team Kaep says he can; the president's legal team believes he cannot.

On Saturday, June 2, Yahoo reported Trump's lawyers wrote a 20-page secret letter to special counsel Robert Mueller in connection with the Russian investigation.

The letter denies Trump can be forced to testify in the Mueller investigation (and therefore, in any investigation) against his will. The letter also reportedly argues the president couldn't have committed any obstruction of justice since he oversees all federal investigations. Mueller is reportedly mulling subpoenaing Trump to appear before a grand jury but has yet to take this unprecedented step.

Should Kaep's lawyers subpoena Trump, then, they would be the first to do so.

While subpoenaing a sitting president is a legal grey area, a New York judge recently ruled that Trump's position does not protect him from being sued, The Hill reports.

A former contestant on The Apprentice, Summer Zervos, filed a defamation suit against Trump. Zervos has accused Trump of sexual misconduct; she claims he defamed her in his dismissal of her accusations.

New York State Supreme Court Judge Jennifer Schecter recently ruled Zervos' suit may move forward. Trump's lawyers plan to appeal the ruling.

It is clear that Kaepernick was on Trump's radar. Last year, Trump specifically addressed Kaepernick while in Louisville, Kentucky, and added some shade. 

"It was reported that NFL owners don't want to pick him up because they don't want to get a nasty tweet from Donald Trump," the president said, according to CNN. "Do you believe that?"

Photo: GIPHY

The road to serving Trump with a subpoena remains quite complicated, however.

Kaepernick's legal team will have to notify the system arbitrator and declare the need for targeted depositions, among other steps. If deemed justifiable, the arbitrator will inform Kaep's team to seek the subpoenas through a district court under the Federal Arbitration Act.

Even should all that happen successfully, Trump would still have the right to ignore or deny the subpoena. The justice system would then have to step in to enforce it. Whether it would do that is unclear.

Until we find out, we'll be paying attention, perched and ready for the inevitable petty!