On Wednesday, the investigation into President Donald Trump and his associates' alleged ties to Russia kicked into another gear. Deputy Attorney General Rod Rosenstein appointed Robert Mueller as special counsel to lead the investigation in the wake of Trump's firing of FBI Director James Comey, and the news follows the revelation that Comey penned a memo accusing Trump of telling him to lay off the Russia inquiry. 

A former FBI Director and U.S. Attorney, Mueller has had a storied career in the U.S. justice system. He was responsible for prosecuting mob boss John Gotti, Panamanian strongman Manuel Noriega, and the bombers of Pan Am Flight 103. He became FBI director just days before the 9/11 attacks, shaping the way the bureau fights terrorism (more on that later). The pick was greeted with great enthusiasm by many who want to see Trump out of office as quickly as possible.

Even people critical of the investigation thus far, and of the people involved in it, have had high praise for both Mueller as the pick and Rosenstein for picking him.

Utah Congressman Jason Chaffetz, the Republican chair of the House Oversight Committee lauded the pick on Twitter, while prominent attorney Benjamin Wittes, who savaged Rosenstein for his role in the James Comey firing, praised the Deputy AG.

At the same time, not everyone was taking the Justice Department's move well.

It's not just Trump supporters on Twitter who had reservations.

After a career going between public service and private law, Mueller was named FBI director in September 2001. He served in the position for 12 years before being replaced by Comey. Once he left the FBI, Mueller went on to become a partner at the law giant WilmerHale. As it turns out, WilmerHale has at least two high-profile clients directly connected to President Trump: Ivanka Trump and her husband, Jared Kushner.

This was quickly pointed out on Twitter, although it was just as quickly pointed out that WilmerHale is a large firm that employs well over 1,000 attorneys, and likely has tens of thousands of clients. There's also no indication that Mueller represented Ivanka or Kushner, and he reportedly stepped down from the firm as soon as he was named Special Counsel. Other critics note that many of the counter-terrorism investigations during his stint at the FBI involved the bureau's agents encouraging and even craft terror plots and then arresting those they convinced to partake, which some consider entrapment.

Not every Republican Member of Congress was as optimistic as Jason Chaffetz, either. Senate Majority Leader Mitch McConnell, whose level of concern over the investigation has never risen beyond wanting "less drama" in the White House, gave a terse "no comment" to CBS.

New York Congressman Peter King, a fervent Trump supporter, reportedly told the AP: "I’m worried with all special counsels because there’s no control over them and they can abuse their power.”

As this point, Mueller will likely hire a staff and quickly take up the investigation. But as with everything related to Trump and Russia, his appointment is clouded by checks and balances. Mueller is likely to have great autonomy in running the operation, but is still answerable to Rosenstein.

And ultimately, Trump can order Rosenstein to fire him, as Richard Nixon did to the special prosecutor investigating Watergate during the infamous Saturday Night Massacre.