Definition
A term of Scots criminal law denoting participation in a crime by a person who is not the principal actor — that is, one who aids, abets, advises, counsels, or otherwise assists in the commission of an offense. A person guilty art and part is treated as a co-principal, sharing full criminal responsibility for the act, rather than being categorized merely as an accessory in the English common law sense. The doctrine collapses the English distinction between principal and accessory: liability attaches to all who participate in the criminal design, whether they gave the original counsel, issued a mandate or warrant for the act, or assisted in its execution.
Common Language
Wiktionary: "The aiding or abetting in the perpetration of a crime."
Editorial note: The Wiktionary definition is serviceable but misleadingly narrow. In Scots law, art and part liability is not limited to active aiding and abetting at the moment of commission — it extends to those who counseled the crime in advance or directed it by authority. The phrase has no counterpart in ordinary modern English and is unknown outside Scots legal contexts, making it unlikely a researcher will encounter it except in legal sources.
Common Confusion
Art and part is frequently glossed in English-language legal dictionaries as equivalent to "accessory" or "principal in the second degree," but this framing imports English common law categories that do not map cleanly onto Scots law. Unlike English law, which historically drew sharp distinctions between principals in the first and second degree and accessories before and after the fact — with different consequences for each — Scots law uses art and part to impose equal guilt on all co-participants. The term should not be read as equivalent to "accessory after the fact," a category Scots law treats separately.
Why It Matters in Research
This term is a jurisdictional marker. Encountering art and part in a historical source signals Scots law — either Scottish court records, Scottish institutional writers, or British sources discussing Scottish criminal procedure. Researchers working in English common law materials who encounter this phrase are almost certainly looking at a document with a Scottish origin or at an English legal dictionary entry cross-referencing Scots practice.
The phrase airt and pairt (the older Scots vernacular spelling) appears in early sources including state trial records and should be recognized as the same term. Burrill flags this spelling explicitly and ties the phrase to the Latin ope et consilio — by aid and counsel — from Roman law. Researchers tracing the intellectual genealogy of complicity doctrine across legal systems will find this connection useful.
For corpus researchers, the term appears almost exclusively in Scots criminal law treatises (Erskine's Institutes, Forbes's Institutes) and in state trial reports, not in English case law or American sources. Its appearance in Black's and Bouvier's reflects the encyclopedic ambition of nineteenth-century American legal dictionaries to document comparative and foreign legal systems, not evidence of any American doctrinal adoption.
Modern Scots criminal law retains the doctrine, now developed through case law and the Criminal Procedure (Scotland) Act 1995, though the phrase art and part has receded in formal usage relative to the underlying concept of joint criminal enterprise. Historical dictionary entries will not reflect this statutory development.
Historical Dictionary Support
All four source dictionaries agree on the core meaning: participation in a crime short of being the primary actor, rendering the participant fully liable. Black's (both editions) and Bouvier's are nearly identical in their formulations, defining the term as the offense committed by one who aids and assists but is not the chief actor, and equating the position to "a principal in the second degree" — a framing that, as noted above, imports English categories somewhat awkwardly.
Burrill is the most useful historical source here. He provides the older spelling (airt and pairt), identifies the phrase as a technical term meaning "contriver and partner," cites Howell's State Trials and the Scottish institutional writers Erskine and Forbes directly, and draws the connection to the Roman law concept of ope et consilio. Burrill also notes that the doctrine extends to accessories before and after the fact — a broader scope than the Black's and Bouvier's definitions suggest.
None of the historical dictionaries address the flattening of the principal/accessory hierarchy that is the doctrine's most significant feature, nor do they situate art and part within the broader history of complicity theory. Researchers seeking substantive doctrinal treatment should go directly to Erskine's Institutes, Book 4, Title 4, rather than relying on dictionary entries as anything more than identification and orientation.
Jurisdictional Note
Art and part is a term of Scots law with no direct counterpart in English common law or American law. Its appearance in American legal dictionaries is comparative and historical, not indicative of any U.S. jurisdiction's adoption of the doctrine. Modern Scots criminal law continues to apply the principle, now supplemented by statute.