President Donald Trump’s latest scandal—a conversation with the president of Ukraine in which Trump allegedly pressured the foreign leader to investigate former Vice President Joe Biden and his son for his own political gain—and the White House’s unwillingness to release details about the incident to Congress appear` to have done what no previous Trump controversies have. On Tuesday, Speaker of the House Nancy Pelosi, who has long resisted the idea of impeaching the president, announced a formal impeachment inquiry. The House will now have to weigh whether the president’s transgressions fall into the impeachable offenses of “treason, bribery, or other high crimes and misdemeanors,” as dictated by the Constitution.

Congress was last forced to consider the meaning of that ambiguous phrase in 1998, when the House formally accused Bill Clinton of “high crimes and misdemeanors” over charges of perjury and obstruction of justice. Ultimately, the Senate voted to acquit Clinton, but the process—and all previous presidential impeachment discussions—did not fully clarify what exactly “high crimes and misdemeanors” means. Two decades later, it’s looking all but certain we’ll have to hash this out again.

While “high crimes and misdemeanors” is commonly thought to refer to significant abuses of presidential power, rather than criminal violations, there are several different camps of interpretation. As Slate explained in 1999, here are the six main readings of the murky term:

Whatever Congress Says It Means

There is evidence that the Founding Fathers were intentionally vague. Initially, the Framers considered defining impeachable offenses as just “treason or bribery” (rather than the ultimate definition of “treason, bribery, or other high crimes and misdemeanors”). They tacked on the additional phrase because George Mason worried that “treason or bribery” was insufficient for removing a president who began to display dictatorial tendencies. [This interpretation posits that] the Framers offered a squishy definition in faith that Congress would know an impeachable offense when it saw one. … Under this theory, senators are urged to look into their hearts—rather than at constitutional scholarship—to decide whether perjury and obstruction of justice warrant removal.

“Political Crimes”

A crime is “political” [under an old legal term] when it involves the misuse of a politician’s official powers. If, for instance, the president accepts a bribe, it’s a political crime; if he shoots his wife, it is not. Support for this theory comes from contemporary speeches and the Federalist Papers. For instance, Federalist No. 65 (Alexander Hamilton) says that impeachable offenses “proceed from the misconduct of public men … from the abuse or violation of some public trust.” Under this theory, [an] obstruction of justice charge would count as impeachable, while [a] perjury charge would probably not.

“Crimes Against the State”

A crime is against the state when it attacks the very core of the state’s apparatus—treason is against the state, jaywalking is not. What’s the evidence for this interpretation? The word “high” is generally understood (in English law) to refer to crimes against the state—bad-mouthing the king is “high treason”; bad-mouthing your brother is “petit treason.” Moreover, the original phrasing, at the Constitutional Convention, was “other crimes and misdemeanors against the United States.” “Against the United States” was stricken by the Committee of Style, a branch of the convention charged with making the document’s language more elegant but prohibited from changing its meaning. The implication is that any competent lawyer in 1789 understood “high crimes and misdemeanors” to refer to crimes against the state. Finally, English commentaries like Blackstone suggest that perjury and obstruction of justice were considered crimes that attacked the core of the justice system. In other words, both crimes are impeachable offenses.

Offenses to Public Sensibilities

Under this argument, a public official has committed “high crimes and misdemeanors” when he offends public sensibilities. The evidence? Impeachment on such grounds was not unheard of in England. For instance, someone named Chief Justice William Scroggs was impeached in 1688 for, among other things, browbeating witnesses and public drunkenness.

Transgressions As Serious As Treason or Bribery

There is a linguistic argument that “treason, bribery, and other high crimes and misdemeanors” implies that high crimes and misdemeanors must be equal in seriousness to treason and bribery. For instance, a competent author wouldn’t write: “murder, child molestation, and other jaywalking-like offenses are impeachable.” Instead, he’d write that “murder, child-molestation, and jaywalking-like offenses are impeachable.” So the inclusion of “other” suggests that the second half of the phrase (“high crimes and misdemeanors”) is comparable in seriousness to the first half (treason and bribery). [T]he phrase applies only to very serious attempts to subvert the constitutional order, which means that perjury and obstruction of justice are not impeachable offenses.

Transgressions Less Serious Than Treason or Bribery