Presidents of the United States have plenty of power. The man who holds the office at the moment, Donald Trump, has wielded it yet again.

He “demanded” that the Department of Justice launch an investigation into whether the FBI planted a snitch inside the 2016 presidential campaign for “political purposes.”

What has gotten tongues wagging is that presidents don’t normally make such demands of DOJ officials who are in the midst of ongoing investigations. They might request it. They don’t demand anything.

I don’t think we should be all that surprised that the president has tossed yet another office tradition into the crapper. He told us he would be an unconventional president. Yep, he’s fulfilled that campaign “promise” … in spades.

Deputy Attorney General Rod Rosenstein, who is overseeing the Russia investigation being conducted by special counsel Robert Mueller, responded the right way. He has assigned the inspector general to conduct the probe into whether the FBI did what Trump has alleged.

Again, to no one’s surprise, Trump has suggested that someone within the Obama administration told the FBI to infiltrate the GOP candidate’s presidential campaign.

This “demand” matter, though, continues to cause angst among those who worry about the integrity and the independence of the DOJ and the FBI from presidential politics.

The investigation that Trump has ordered will seek to ascertain the motive behind any directive that was issued by the FBI. Indeed, the law enforcement agency is empowered to solicit information from confidential sources. When the FBI gets word, therefore, of Russian interference in our presidential election, isn’t it proper for the agency to get to the bottom of it all?

The president has ordered an investigation into an investigation.

That isn’t normal by any stretch. Donald Trump has exercised the power he possesses legally. What’s legal, though, isn’t always right.