Definition
Solidary describes an obligation or right shared among multiple parties in such a way that each party is fully liable for the whole — not merely for a proportionate share. The term originates in civil law and has no precise single-word equivalent in common law tradition, though it maps closely onto the common law concept of "joint and several" liability.
A solidary obligation is one in which each obligor owes the full performance to the obligee, who may demand complete satisfaction from any one of the debtors. Payment or performance by one extinguishes the obligation as to all. Civil law systems, including Louisiana and Quebec, use solidary as a term of art with specific statutory definition and distinct subcategories unknown to common law.
The civil law conception of solidary is broader than the common law's joint and several. In civil law, solidarity can also arise on the creditor's side (active solidarity), meaning any one of multiple creditors may demand full performance from the debtor. This active form has no strong common law parallel and is often overlooked in comparative research.
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Common Language
Modern common usage (Wiktionary): Having community of interests and responsibilities; showing solidarity.
Historical common usage (Webster's 1913): Having community of interests and responsibilities. "Men are solidary, or copartners; and not isolated."
The common usage tracks the general idea of shared responsibility but lacks all legal precision. In ordinary English, solidary implies mutual social or moral commitment — workers standing together, nations in alliance. In law, solidary describes a specific structural relationship among obligors or obligees that triggers defined legal consequences: full liability on each, with contribution rights among co-debtors and extinguishment upon full performance. The moral resonance of the common word can mislead researchers into underestimating how technically the legal term operates.
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Common Confusion
SOLIDARY vs. JOINT AND SEVERAL: These terms are functionally close but not identical. Joint and several is the common law formulation; solidary is the civil law formulation. In practice, the outcomes often align — each co-debtor is liable for the whole — but the doctrinal mechanics differ. Civil law solidarity is governed by statutory rules addressing contribution, interruption of prescription, and the effect of one debtor's insolvency on the others. Researchers applying common law assumptions to solidary obligations in civil law jurisdictions (particularly Louisiana) will find gaps. The terms should not be treated as interchangeable in legal drafting or historical analysis.
SOLIDARY vs. IN SOLIDO: In solido is the Latin phrasing for the same concept and appears frequently in older civil law texts and Louisiana decisions. The terms are substantively equivalent, but in solido tends to appear in older sources and in solido obligations in older codes, while solidary is the modern statutory preference in Louisiana's Civil Code.
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Recognized Forms
/SUBTYPES
Passive solidarity (solidary obligation): Multiple debtors each owe the full performance to a single creditor. The most common form in commercial practice.
Active solidarity: Multiple creditors, each of whom may demand full performance from the debtor. Rare in practice but doctrinally significant in civil law systems.
Imperfect solidarity (in solido): Recognized in some civil law jurisdictions for cases where multiple debtors owe the same thing to the same creditor by different obligatory relationships, without a true solidarity arising from agreement or statute. Louisiana jurisprudence has used this category, though it remains contested.
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Why It Matters in Research
Researchers working in Louisiana law, Quebec law, or comparative civil law will encounter solidary throughout primary sources — constitutions, codes, contracts, and judgments. The Louisiana Civil Code uses solidary as the governing term, and its rules on solidarity diverge enough from common law joint-and-several doctrine that research methodology must account for the difference.
In historical sources predating Louisiana's Civil Code revisions (substantially revised in 1984), you will find in solido used where modern sources say solidary. This is not a substantive change but a terminological modernization; failing to search both terms will produce gaps in a historical survey.
Common law sources — including most of the historical legal dictionaries on this shelf — treat solidary briefly, if at all, as a civil law curiosity. Black's 2nd Edition captures the core definition but does not develop the active/passive distinction or the contribution mechanics. Researchers should not rely on common law dictionaries for the full doctrinal content of solidary obligations.
For cross-jurisdictional contracts, the choice between solidary and joint and several in drafting can affect interpretation in civil law courts. This is a live issue in transactions touching Louisiana, Quebec, or civil law systems internationally.
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Historical Dictionary Support
Black's Law Dictionary (2nd Ed.) identifies solidary as a civil law term meaning that "each is liable for the entire amount, and not merely for his proportionate share," and signals that the civil law usage is broader than the joint-and-several common law analogue — noting it also covers cases beyond what common law contemplates, though the entry is incomplete at that point. This is the right instinct: the civil law concept encompasses active solidarity on the creditor's side, a dimension Black's gestures toward but does not fully develop.
The entry's framing as a civil law term "corresponding to" joint and several is useful but should be treated as an approximation rather than an equation. Historical legal dictionaries generally treat solidary as a foreign import requiring translation into common law terms, which can obscure the features that make civil law solidarity distinct. Researchers should move from these dictionary definitions to the civil law primary sources — particularly the Louisiana Civil Code articles on obligations — to get the full picture.
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Jurisdictional Note
Solidary is a term of art in Louisiana law, where it is defined and governed by the Louisiana Civil Code. Other American states use joint and several for functionally similar results but through different doctrinal machinery. In Quebec and other civil law systems, solidary obligations follow analogous but not identical rules. Importing common law joint-and-several case law to interpret solidary obligations in Louisiana courts is an error that has produced confusion in cross-border commercial litigation.
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