Plain-English AI definitions for legal professionals. For what bars actually require, see the Legal AI Compliance Register.

Closed model

Using AI Last reviewed 2026-06-11

Definition An AI model whose weights remain private, accessible only through the provider's app or API—as with the leading commercial models. Users send data to the provider's servers and accept its terms to use the model.

In more depth

Closed models are typically the most capable available and come with managed infrastructure, safety tuning, and support, but the model itself cannot be inspected or self-hosted. Data handling is governed by the provider's contract, making terms about retention, training on inputs, and security certifications the central diligence questions. Most legal AI products are built on closed models accessed through enterprise agreements.

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About the editor: MHSB Solutions, Research desk. MHSB Solutions is not a law firm. This glossary is educational information, not legal advice.

Educational information, not legal advice. AI terminology and tools change quickly; definitions reflect usage as of the last-updated date. For what bar associations and courts actually require of lawyers using AI, see legalaicompliance.help and consult a licensed attorney in your jurisdiction.