Definition
To suppress, in law, means to exclude, withhold, or put an end to something — most commonly evidence in a criminal proceeding, or conduct that the law forbids from continuing. The term carries two principal legal meanings that operate in distinct contexts:
1. To suppress evidence: In criminal procedure, to obtain a court order excluding evidence from trial on the ground that it was obtained unlawfully or in violation of a constitutional right. The suppression of evidence is the primary remedy for Fourth Amendment violations and for certain Fifth and Sixth Amendment breaches. Evidence that is suppressed cannot be used in the prosecution's case-in-chief, though suppressed evidence may sometimes be used for impeachment purposes.
2. To suppress conduct or a thing: To put a stop to something actively occurring — to quell, prohibit, or terminate. A court may suppress a nuisance, suppress a riot, or suppress a publication. In this sense, to suppress means to eliminate what exists, not merely to prevent what might arise in the future.
Common Language
Modern common usage (Wiktionary): To put an end to, especially with force; to crush or prohibit. To restrain or repress, such as laughter or an expression. To prevent publication. To forbid the use of evidence at trial because it is improper or was improperly obtained.
Historical common usage (Webster's 1913): To overpower and crush; to subdue; to put down; to quell. To retain without disclosure; to conceal; not to reveal; to prevent publication of.
The ordinary sense of suppress — to hold back, hide, or crush — captures the intuition but misses the procedural architecture. In legal usage, suppression of evidence is not an act of concealment; it is a formal judicial remedy. A motion to suppress is the mechanism by which a defendant asks the court to exclude evidence. The evidence is not hidden; it is ruled inadmissible. Researchers reading historical sources should note that suppression of a document and suppression of evidence at trial are meaningfully different acts.
Common Confusion
Suppress vs. exclude: These terms are often used interchangeably in modern criminal procedure, but they are not identical. To suppress evidence is to obtain a pretrial ruling that certain evidence is inadmissible; exclusion is the broader outcome. All suppressed evidence is excluded, but not all excluded evidence was suppressed — evidence may be excluded on hearsay, relevance, or foundation grounds without any suppression motion.
Suppress vs. expunge: Suppression removes evidence from a trial; expungement removes a criminal record from public access. They address different stages and different concerns. A successful suppression motion does not expunge the underlying arrest or investigation.
Suppress vs. prohibit: Historical dictionaries occasionally conflate these. Bouvier specifically flags the distinction: to suppress is to put a stop to something already existing; to prohibit is to prevent something from occurring. A court suppresses a nuisance already underway; it prohibits anticipated conduct. Anderson's note — "never, therefore, to license or sanction" — reinforces that suppression is a form of interdiction, but the temporal distinction from prohibition is important in statutory interpretation.
Why It Matters in Research
The dominant modern legal use — suppression of evidence in criminal proceedings — is largely a twentieth-century procedural development tied to constitutional exclusionary doctrine. Researchers working in pre-twentieth-century materials will encounter suppress primarily in its older senses: suppressing publications, riots, combinations, or nuisances. Do not assume that a historical reference to suppression carries the Fourth Amendment valence now familiar to practitioners.
In criminal procedure materials, the motion to suppress is the pivotal pretrial vehicle. Research timelines matter: the exclusionary rule as applied to federal prosecutions dates to the early twentieth century, and its extension to state courts came later. Historical sources from before this development will not reflect suppression as an evidentiary remedy at all.
Jurisdictional variation affects procedure, not concept: states differ in whether suppression motions must be brought before trial (waiver rules vary), what hearings are required, and the scope of the exclusionary remedy. When researching suppression doctrine across jurisdictions, pay attention to how each jurisdiction treats inevitable discovery, independent source, and attenuation exceptions — each narrows what suppression actually accomplishes.
For researchers using Bouvier: the entry's discussion of suppressio veri (concealment of truth) sits adjacent to suppress and addresses a distinct contract-law concept. Do not conflate the two. Suppressio veri vitiates contracts when a party had a duty to disclose; evidentiary suppression in criminal procedure is a constitutional remedy doctrine. The Latin maxim appears in equity and insurance law discussions; the procedural suppression doctrine appears in criminal law.
The corpus connection between suppression and Fourth Amendment standing is important: only a defendant whose own rights were violated may move to suppress. Researchers tracing suppression doctrine should track standing doctrine alongside the suppression remedy itself, as they developed in tandem.
Historical Dictionary Support
Anderson and Bouvier largely agree on the core: to suppress is to put a stop to something actually occurring, and it does not extend to the preventive function of prohibition. Bouvier's distinction — "does not extend to preventing by suppressing what may lead to a thing" — reflects a careful parsing of the term's scope that remains useful in statutory construction today when a legislature uses suppress in an operative provision.
Both historical sources predate the constitutional exclusionary rule as a developed doctrine, so neither addresses suppression of evidence in the Fourth Amendment sense that dominates modern criminal procedure. This is the most significant gap in the historical dictionary record for this term. Researchers relying on Anderson or Bouvier alone will find no guidance on the motion to suppress as it functions today.
Bouvier's inclusion of suppressio veri — concealment of truth — is useful as a separate doctrine in contract and insurance law, and its placement adjacent to suppress is suggestive of the broader family of suppression-related concepts in equity. The principle that suppression of a material fact, when disclosure is required, vitiates a contract remains active in insurance law and certain fiduciary contexts.
Jurisdictional Note
In federal courts, suppression motions are governed by Federal Rule of Criminal Procedure 12, which generally requires such motions to be made before trial or they are waived. State procedures vary, with some jurisdictions permitting suppression issues to be raised mid-trial in limited circumstances. The substantive standard for what evidence is suppressible is constitutional where Fourth, Fifth, or Sixth Amendment rights are at stake, but states may provide broader suppression remedies under their own constitutions.
Encyclopedia Cross-Reference
Pretrial Motions — Motion to Suppress Evidence (The Law Mind Criminal Law Encyclopedia)