After nearly two years of jockeying with Congress over the IRS's history of discriminating against conservative nonprofit groups, former official Lois Lerner won't be charged with a crime for defying a congressional subpoena and refusing to answer questions. U.S. Attorney Ronald Machen, on his last day in office, told House Speaker John Boehner in a seven-page letter that Lerner could wrap herself in the U.S. Constitution's Fifth Amendment, even though she offered a self-serving opening statement before clamming up during a May 22, 2013 hearing. Lerner has long been in the GOP's crosshairs because she led the IRS department tasked with approving nonprofit groups' applications for tax-exempt status. Beginning in 2010, the department gave conservative groups with words like 'patriots' or 'tea party' in their names extra scrutiny, slow-walking their applications and keping many in limbo for years. The House Oversight and Government Reform Committee had subpoenaed Lerner after she refused to testify voluntarily about her role in the scandal. SCROLL DOWN FOR VIDEOS AND THE DOJ'S LETTER TO BOEHNER . I'LL TELL THE TRUTH ... UNLESS I'M TAKING THE FIFTH: Former IRS official Lois Lerner insisted on her innocence in an opening statement during a 2013 congressional hearing, and then refused to answer lawmakers' questions – a choice that the Obama administration now says was perfectly legal . U.S. Attorney for the District of Columbia Ronald Machen (left) dropped his bomb on Congress just one day before leaving office to return to private legal practice . Emailed? Machen's letter was addressed to House Speaker John Boehner (left), who was in Jerusalem visiting with Israeli Prime Minister Benjamin Netanyahu (right) When she refused again to answer questions during a second hearing on March 5, 2014, House Republicans prepared a criminal contempt citation and referred the case to the Justice Department once it was approved. California Republican Rep. Darrell Issa, then the Oversight committee's chairman, told Lerner in one hearing that she had 'effectively waived your rights' by defending herself under oath. 'I have not done anything wrong,' Lerner had said in the 2013 hearing. 'I have not broken any laws, I have not violated any IRS rules or regulations, and I have not provided false information to this or any other congressional committee.' Machen told Boehner on Tuesday that since Lerner had only made 'general claims of innocence,' she was within her rights to refuse to answer questions. 'Ms. Lemer's general denials of wrongdoing did not amount to "testimony" about the actual facts under the Committee's review,' he said. 'The Fiflh Amendment to the Constitution would provide Ms. Lerner with an absolute defense, should she be prosecuted ,,, for her refusal to testify.' Machen's March 31 letter arrived on Capitol Hill just a day before his resignation took effect after a five-year stint as Washington, D.C.'s top federal prosecutor inside the Justice Department. President Barack Obama named him to his post in December 2009. Reactions swept through the nation's capital as word spread that Lerner was, legally, in the clear. 'Once again, the Obama administration has tried to sweep IRS targeting of taxpayers for their political beliefs under the rug,' Boehner spokesman Michael Steel told Daily Mail Online. 'But unaccountable federal bureaucrats using their power to attack the First Amendment strikes at the heart of our democracy, and the American people deserve the truth.' 'The White House,' said Steel, 'still has the opportunity to do the right thing and appoint a special counsel to examine the IRS’ actions.' Attorney General Eric Holder has refused repeatedly to bring in a special counsel, instead appointing attorney Barbara Bosserman to lead an internal probe. Republicans see Bosserman as a politically conflicted choice: Federal Election Commission records show that she donated a total of $6,750 to  Obama’s campaigns and to the Democratic National Committee. SWITCH: During the tea party targeting hearings, it was Oversight committee ranking Democrat Elijah Cummings (left) who was regularly exasperated – but now Darrell Issa (right), his Republican foil at the time is frustrated by a lack of accountability for Lerner . Tea party groups and other conservative organizations seeking tax-exempt status were kept in limbo for years while the IRS often green-lighted liberal groups in weeks or months . Issa, whose outrage led to the congressional contempt citation against Lerner – and one against Holder, for refusing to turn over documents related to the scandal – was livid. 'Refusing to prosecute Mrs. Lerner and Mr. Holder after they were held in contempt by a vote of the House of Representatives sends a disturbing message that it is permissible for senior government officials to lie to Congress and to ignore subpoenas for information vital to Congressional investigations,' he said Wednesday in a statement. Issa's successor as chairman of the Oversight committee, Utah Republican Rep. Jason Chaffetz, said Machen's letter 'exhibits a disregard for the rule of law' and scoffed at his objectivity. 'It is unclear whether the Administration directed Mr. Machen not to prosecute Lois Lerner, or whether he was motivated by an ideological kinship with IRS’s leadership,' Chaffetz said. 'The Committee will continue to pursue its ongoing investigation into the targeting of American citizens based on their political beliefs. Our goal is to ensure that the people responsible, including Lois Lerner, are held accountable.' Lerner's attorney, William Taylor, said in a statement that his client 'looks forward to moving on with her life.' 'It is unfortunate that the majority party in the House put politics before a citizen's constitutional rights,' Taylor said. DOJ Letter to Boehner About Lois Lerner uploaded by DailyMail.com .
Justice Dept. sent 7-page letter to House Speaker John Boehner explaining why the former IRS official was allowed to plead the Fifth Amendment .
Federal prosecutor in charge of the case sent his decision to Capitol Hill on the last day before his own resignation took effect .
Lerner offered a self-serving opening statement during a 2013 hearing, but refused to take questions even though she was under subpoena .
Hearing focused on the IRS's habit of targeting conservative groups with special scrutiny based on words like 'patriots' or 'tea party' in their names .
The DOJ says she can't be prosecuted for defying the subpoena 'because she made only general claims of innocence' and offered few details .