Deputy Attorney General Rod Rosenstein gave his reason for naming a special counselto investigate Russian interference in the 2016 election: trust.Rosenstein said it is important Americans "have full confidence"in the "outcome" of the Russia investigation.For that to happen, Rosenstein said, he needed to name a person"who exercises a degree of independence from the normal chain of command."That person is Robert Mueller, a former federal prosecutor and FBI director.His selection Wednesday was praised by both Democrats and Republicans.Rosenstein's order says Mueller can investigate Russia's effortsto interfere with the presidential election,possible connections between Russia and Trump campaign officialsand any other matters that "arise directly from the investigation."Mueller will have more independence than the 94 U.S. attorneyswho normally oversee criminal investigations.But he won't have complete independence.Mueller, unlike other federal prosecutors,will not be subject to day-to-day supervisionby the attorney general and other Justice Department officials.But the deputy attorney general can overrulehis "prosecutorial or investigative decisions."Rosenstein, the deputy attorney general, is overseeing the Russian investigationbecause Attorney General Jeff Sessions removed himself.Sessions withdrew because he worked on the Trump campaign and met with Russian officials.Mueller's appointment came after some unexpected developments in the Russia investigation.Last week, President Donald Trump dismissed FBI Director James Comey,who was overseeing the FBI's collection of evidence.The dismissal was followed by reports claiming that Trump had asked Comeyto drop an investigation of his former national security adviser, Michael Flynn.Another report said Trump had asked Comey if he would be "loyal" to him.The White House denied both claims but some Democratssay Trump should be investigated for obstruction of justice.John Barrett is a law professor at St. John's University in New York.Barrett had earlier worked for a special federal prosecutor.He said obstruction of justice is a complex law.Among other things, it makes it a crime to obstruct,influence or impede any official proceeding for corrupt reasons.Barrett said Trump's actions should be investigated.It will depend on whether Comey and others saw Trump's comments as threats, Barrett said.Special counsels have only been named twice.The last time was in 2003 when prosecutor Patrick Fitzgeraldinvestigated who leaked the identity of a CIA officer, Valerie Plame.“Watergate” is the best known case involving a special prosecutor.Archibald Cox was appointed to investigatewhether President Richard Nixon had obstructed justice.The case centered on whether Nixon covered uphis administration's involvement in the 1973 break-inat Democratic headquarters in the Watergate building.Nixon resigned from office in 1974-- as Congress was ready to begin proceedings to remove him from office.Another well-known case was the investigation of President Bill Clinton by Kenneth Starr.It started out as an investigation into a real estate deal known as Whitewater.But it led to Starr reporting that Clinton had covered up an affair with a White House intern.Special prosecutors had more independence than a special counsel,the job Mueller now has.But the law establishing the prosecutor position ended in 1999.The Mueller investigation probably will not be finished quickly.The Washington Post reported that, on average,previous investigations by special counsels or prosecutors took a little over three years.Ari Fleischer, the press secretary during the George W. Bush administration,tweeted Thursday that Mueller will not take any more time than needed."Starr was 48 when named special prosecutor," he tweeted."Fitzgerald was 43 when named special counsel.Mueller is 72. He won't want this to take years."And I'm Anne Ball.