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

How models workLast reviewed 2026-07-01

DefinitionAdditional training applied to an existing AI model using a smaller, specialized dataset so it performs better on a particular domain or task—such as legal drafting conventions—without building a model from scratch.

In more depth

Fine-tuning adjusts a pretrained model's weights with targeted examples, in contrast to retrieval-augmented generation, which leaves the model unchanged and supplies documents at question time. Legal technology vendors use fine-tuning to teach models domain vocabulary, formats, and tone. Material used for fine-tuning becomes part of the model's learned behavior, so client data should not be used for it without clear authority and safeguards.

Further reading: Wikipedia.

Related terms

Foundation modelTraining dataRetrieval-augmented generation (RAG)Model weights

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.