https://www.ftc.gov/system/files/ftc_gov/pdf/P214800%20Dark%...

"Coined in 2010 by user design specialist Harry Brignull, the term 'dark patterns' has been used to describe design practices that trick or manipulate users into making choices they would not otherwise have made and that may cause harm."

Not sure if this reference to a definition is the same thing as saying it's the legal definition, but this is at least in a document as /a/ definition on the Federal Trade Commission's website.

Are you asking me to see how this mechanism applies to this definition?