In the United States, impeachment refers to the process through which a public official can be investigated for removal from office, which may also result in his or her prohibition from holding future public office. The US Constitution stipulates that "the President, the Vice President, and all civil officers" of the federal government may be subject to impeachment and removal if suspected of "treason, bribery, or other high crimes and misdemeanors." The founders included the language "high crimes and misdemeanors" to refer to activities or behaviors committed by a public official that do harm to the state, regardless of whether law enforcement has recognized the behavior as criminal or brought charges. 

The power to impeach federal officials lies solely with Congress. The US House of Representatives (the House) is responsible for investigating and filing impeachment charges, while the Senate acts as the court before which impeachment trials are heard. The Senate's verdict is limited to three options: acquittal, removal from office, or removal plus prohibition from holding future office. Because impeachment is a political process rather than a criminal one, any charges brought by law enforcement are handled by the courts. Impeachment, therefore, can be used to investigate a person's fitness to hold office and allegations of criminal and unethical behavior. In addition to the federal government, every state except Oregon, which relies on recall elections to remove elected officials, allows for impeachment of state officials. 

Federal impeachment proceedings have been launched over sixty times, but as of early 2019 the House has only voted to impeach twenty individuals since the founding of the government in 1789—fifteen judges, three presidents, one senator, and one cabinet secretary. Senate trials have resulted in eight convictions, eight acquittals, three dismissals, and one resignation. The House impeached presidents Andrew Johnson (1808–1875) in 1868, Bill Clinton (1946–) in 1998, and Donald Trump (1946–) in 2019, sending them to trial before the Senate where no case garnered the votes necessary for conviction. 

Since the start of the twenty-first century, lawmakers have proposed impeachment several times, however only President Donald Trump was impeached. In 2008, for example, Representative Dennis Kucinich (D-OH) accused President George W. Bush (1946–) and Vice President Dick Cheney (1941–) of war crimes and introduced thirty-five articles of impeachment against the president but no action was taken on the measure. However, on December 18, 2019, the US House of Representatives voted to impeach President Donald Trump (1946–) after accusations he asked foreign leaders to investigate the son of political rival Joe Biden (1942–). He was acquitted on February 5, 2020. 

Role of the Legislative Branch

The Constitution grants the House the sole power to conduct formal impeachment proceedings, but people who do not serve in Congress may participate in initiating the process. Impeachment may be instigated on advice from a government body; by recommendation from the president; following charges brought by state, territorial, or federal law enforcement; or through petition by private citizens. Depending on the circumstances of the case, impeachment resolutions are submitted either to the House Committee on the Judiciary or, if further investigation is needed, to the House Committee on Rules, which then sends the resolution to the appropriate investigative committee. The investigative committee evaluates the charges outlined in each article of impeachment, conducts a vote, and reports its recommendation to the House in advance of the full membership's impeachment vote. When a simple majority of the House votes in favor of proceeding with trial in the Senate, an official has been impeached. 

After the House vote, the Senate notifies the accused of when to appear and enter his or her plea. If the accused chooses not to appear or send legal representation, the Senate assumes a plea of not guilty and sets a trial date. Most impeachment trials are presided over by the president of the Senate, a position held by the sitting vice president. For presidential and vice-presidential impeachment trials, the chief justice of the US Supreme Court presides. After charges, arguments, and evidence are presented, senators deliberate and then hold an open-session vote on each article of impeachment. To achieve a conviction, a supermajority of at least two-thirds of the Senate must find the accused guilty on at least one article of impeachment. A guilty conviction results in removal from office, and the Senate may choose to disqualify the person from holding future office with a simple majority vote. 

As modern impeachment debates have tended to coincide with criminal investigations, many citizens think that the same burden of proof is required for impeachment charges and conviction as is required for criminal charges and conviction. However, while some impeachable offenses are criminal, and some criminal offenses are impeachable, many impeachable offenses are not criminal, and many criminal offenses do not merit impeachment. Conflicts of interest, for instance, do not need to rise to the US Department of Justice's (DOJ's) standard of criminal fraud to warrant impeachment. 

The differences between criminal and impeachment standards can make impeachment seem arbitrary or confusing, but constitutional scholars stress that the differences are purposeful. As the legislative branch's mechanism for removing public officials, impeachment is also the people's mechanism for removing public officials. As such, it is seen as central to maintaining the system of checks and balances established by the framers. Neither the executive nor the judiciary has the power to impeach, and Congress' process need not consider the actions or preferences of either branch. Because the DOJ has never brought a criminal indictment against a sitting president, the question of whether such an action in itself would merit impeachment remains an open question as of early 2020. 

Presidential Impeachment

While a presidential impeachment has never resulted in a conviction and removal from office, in July 1974 the House Judiciary Committee approved three articles of impeachment against President Richard Nixon (1913–1994) after a criminal investigation linked a 1972 break-in at the Democratic National Committee to operatives for Nixon's reelection campaign. The approved articles charged Nixon with abuse of power, contempt of Congress, and obstruction of justice, and the House was all but guaranteed to send the charges to the Senate for trial, where conviction was likely. Nixon chose to resign from office in advance of the House vote. Lawmakers and political scientists traditionally regard impeaching a president as an absolute last resort, noting that the process can damage the country's reputation, add to political instability, and hurt the economy. 

Many stakeholders in US politics also argue that presidential impeachment is too vulnerable to being used as a weapon to gain power because it is kept separate from criminal and civil courts and limits its consequences to federal office-holding. With a two-party system and a hyperpartisan climate, some critics argue that the weaponization of impeachment can be seen in how commonplace it has become to propose presidential impeachment since the 1980s. Impeachment resolutions have been introduced against twelve US presidents, including Ronald Reagan (1911–2004) and each of the five presidents who have succeeded him. This means that, as of February 2019, half of all presidents against whom impeachment resolutions have ever been introduced assumed office in 1980 or later. Most of these resolutions never left committee. However, both Clinton and Trump were impeached. 

Conversations regarding the impeachment of Republican president Donald Trump began shortly after his election. Citizens, politicians, and political commentators have raised concerns about possible conflicts of interests involving his many business properties; campaign coordination with Russian agents; violations of campaign finance law; mishandling of donations by his inaugural committee; leveraging military aid to other countries for personal political gain; and a variety of other actions that may constitute impeachable offenses. While some activists and lawmakers indicated support for impeachment, other opponents of the president expressed reservations. 

Following Trump's firing of FBI director James Comey in May 2017, Trump faced increased accusations of trying to impede investigations into Russian interference in the 2016 elections. Two months later, House members filed the first articles of impeachment against Trump for obstruction of justice. In November and December 2017 congressional Democrats again filed articles of impeachment against the president for undermining the freedom of the press, abuse of power, encouraging social unrest, and violations of both foreign and domestic emoluments clauses, which are anticorruption provisions barring federal officials from using the position of their office for personal enrichment or taking gifts from nongovernment sources that may influence policymaking. 

Political scientists argue that ongoing debates regarding Trump's impeachment exemplify the political nature of the process and the effect that timing and public opinion have on the potential outcome. At the time of Trump's inauguration, Republicans held the House and did not support impeachment, so most Democratic representatives opposed pursuing it simply because they did not have the votes. When Democrats gained House control in 2019, the power shift provided the simple majority needed to secure impeachment in the House. With the Senate still in Republican control, however, Trump's removal from office remained unlikely. 

Following allegations in a 2019 BuzzFeed article that Trump had instructed his personal attorney, Michael Cohen, to lie to Congress, several Democratic lawmakers again expressed support for impeachment investigations. However, many in the House, including Speaker of the House Nancy Pelosi, did not believe that beginning a formal impeachment process was warranted at the time, as there would need to be support from a simple majority of the House of Representatives (including representatives in swing or more conservative districts) to formally impeach the president, and two-thirds of the Republican-led Senate to convict the president. 

This changed on September 24, 2019, when Pelosi announced an impeachment inquiry of Trump, alleging abuse of power. A government whistleblower charged that Trump had urged an investigation of political rival Joe Biden and his son Hunter by newly elected Ukrainian president Volodymyr Zelensky, holding back almost $400 million in promised military aid and dangling a meeting at the White House in exchange. After the announcement of the inquiry, the White House said it would not cooperate and attempted to block State Department officials and others from testifying. Despite these actions, House investigative committees, made up of both Democrats and Republicans, began issuing subpoenas and held closed hearings that featured a series of depositions from various diplomats, ambassadors, and other government officials that continued through October. On October 31, a majority of the US House voted (232-196) on partisan lines to endorse the impeachment inquiry and put rules in place for a public inquiry process. On December 18, 2019, the House voted to impeach Trump on two articles of impeachment: abuse of power and obstruction of Congress. The Republican-led Senate voted not to hear witnesses or admit documents as evidence, and on February 5, 2020, acquitted him on both articles of impeachment. 

Despite the political deliberations in Washington, historians note that the people do, in fact, play a crucial role in impeachment. Any presidential impeachment conviction would almost certainly require congressional members of the president's own party to turn against the president, making approval ratings a useful barometer for judging whether impeachment will backfire. According to polling website FiveThirtyEight, public support for impeachment rose and fell between August 2018 and August 2019 between 35 and 45 percent. However, the number of those who disapproved outnumbered those who approved until mid-September 2019. At that point, those who approved of impeachment surpassed those who disapproved. According to a Quinnipiac University poll conducted on October 23, 2019, after several weeks of testimony by career diplomats and others on the questions surrounding Trump's alleged pressure on Ukraine for personal political gain, 55 percent of American voters approved of an impeachment inquiry and 43 percent disapproved, though this was mainly spilt along party lines, with 93 percent of Democrats, 58 percent of independents, and only 10 percent of Republicans approving. Opinion polls taken in the days before the Senate vote to acquit the president occurred on February 5, 2020, showed opinion was still spilt along party lines. Among Democrats, 84.4 supported impeachment, while only 43.3 percent of independents and 12.6 percent of Republicans did. When it came to removing the president, about 48.4 percent of all those surveyed supported removal while 46.9 did not.