lawfully
adv.in a way that follows the law or is allowed by legal rules. You use this to describe actions that are officially permitted.
adv.in a manner that conforms to the law or is permitted by legal statutes.
“The business operates lawfully and pays all its taxes.”
“The police confirmed that the protesters were acting lawfully as long as they remained on public property.”
“The tribunal must determine whether the evidence was lawfully obtained before it can be admitted into the formal proceedings of the court.”
Typically follows the verb it modifies or appears at the end of the clause.
Learners often use the adjective 'lawful' when the adverbial form 'lawfully' is required to modify an action.
“There is little they can do in those 60 days that would allow them to lawfully remain in the U.S.”
From Middle English lawefully, lawfulliche, lawefulliche; equivalent to lawful + -ly.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.