Definition
"High crimes" refers to serious offenses against the state, public trust, or constitutional order — most notably as one half of the constitutional impeachment standard, "high crimes and misdemeanors." The phrase does not describe a discrete criminal charge or statutory offense; it is a constitutional term of art used to define the threshold for removing federal officers, including the President, Vice President, and civil officers, from office.
The phrase "high crimes and misdemeanors" appears in Article II, Section 4 of the U.S. Constitution as one of the grounds for impeachment, alongside treason and bribery. "High" in this context does not mean serious in degree of ordinary criminal law — it refers to offenses against the high office itself, acts of abuse of power, betrayal of public trust, or conduct fundamentally incompatible with the duties of constitutional office. Whether the underlying act would constitute an indictable crime under ordinary criminal law is a contested but historically recurring question in impeachment proceedings.
Common Language
Modern common usage (Wiktionary): Plural of "high crime" — used informally to mean a very serious or grave criminal act.
Historical common usage (Webster's 1913): Not separately defined; "high" as an adjective in legal contexts conveyed elevated rank, gravity, or relation to the sovereign or state.
The gap between common and legal usage here is significant. In ordinary speech, "high crimes" sounds like an aggravated or especially severe category of criminal wrongdoing — a matter of degree. In constitutional law, the term is not primarily about severity on a criminal scale at all. It describes offenses against the constitutional order and public trust, which may or may not overlap with indictable crimes. An act could qualify as a "high crime" for impeachment purposes without being a crime at all, and conversely, a prosecutable felony might not meet the constitutional threshold if it bears no relationship to the officer's public duties.
Common Confusion
"High crimes and misdemeanors" is frequently misread as two separate criminal categories mapped onto ordinary criminal law — that is, as if "high crimes" means felonies and "misdemeanors" means lesser offenses. This mapping is historically and constitutionally inaccurate. The phrase was inherited from English parliamentary practice, where "high crimes and misdemeanors" referred collectively to political offenses and breaches of public trust by persons in positions of power — not to the felony/misdemeanor distinction in common law criminal procedure. The two words together form a unified term of art. Neither half should be read through the lens of modern criminal code classifications.
Why It Matters in Research
Researchers encounter "high crimes" almost exclusively in two contexts: constitutional impeachment scholarship and historical sources predating the stabilization of American criminal law categories.
In impeachment research, the critical navigational point is that Congress — not courts — has functioned as the authoritative interpreter of what "high crimes and misdemeanors" means, and that interpretation has shifted across proceedings. There is no binding judicial definition. Researchers tracing the phrase through congressional records, committee reports, and floor debates will find the standard invoked expansively in some proceedings and narrowly in others, with little doctrinal consistency across eras. Primary source research must account for this political variability.
In older legal dictionaries and case reporters, "high crimes" occasionally appears in a non-impeachment context — as a loose descriptor for serious offenses below felony or as a rhetorical marker for grave moral transgressions. The Connecticut case quoted in Black's ("such immoral and unlawful acts as are nearly allied and equal in guilt to felony, yet, owing to some technical circumstance, do not fall within the definition of felony") reflects this pre-modern usage and should not be imported into constitutional impeachment analysis. Conflating these two usages — the historical common-law descriptor and the constitutional impeachment standard — is a recurring research error.
Jurisdictional variation matters here in a specific way: the impeachment standard in Article II applies to federal officers. State constitutions have their own impeachment language, which may differ. Researchers working on state-level impeachment proceedings should not assume the federal constitutional standard governs.
Historical Dictionary Support
Black's Law Dictionary's entry for "high crimes and misdemeanors" reflects the older common-law gloss — offenses morally equivalent to felony but technically excluded from that category. This definition is descriptive of one historical usage but is incomplete as a guide to constitutional meaning. It does not address the English parliamentary origins of the phrase, nor does it capture the dominant understanding in constitutional scholarship that "high crimes and misdemeanors" encompasses non-indictable abuses of power.
The historical dictionaries are most useful here for what they reveal about the phrase's contested past rather than for any settled definition they provide. Researchers should treat Black's entry as a data point about how American lawyers in a given period understood the term, not as an authoritative construction of the constitutional standard.
Jurisdictional Note
The impeachment standard in Article II, Section 4 applies only to federal officers. Most state constitutions include their own impeachment provisions, often using different language. Some state standards are broader, some narrower, and state courts have occasionally exercised judicial review over impeachment proceedings in ways federal courts have declined to do.