“No signal” refers to the practice of citing a source and not preceding it with a signal. This is done by making a statement and citing a source (e.g., a judicial opinion, book, or website) without first including a word or phrase to indicate the relevance of that source.
In academic writing, not using a signal means that the source directly supports the statement without requiring even a small logical inference. In this kind of writing, no signal is required only if the statement includes a direct quotation from the source, objectively re-states a claim or piece of data from the source, or references the source informally such that the citation simply gives more information about where the source may be found.
[Last updated in July of 2023 by the Wex Definitions Team]