In the American legal system, argumentative is an evidentiary objection raised in response to a question which prompts a witness to draw inferences from facts of the case.
[1] A lawyer on direct examination asks his witness, a layman with no legal training, "So John Doe was driving negligently?"
In this context, "negligently" is a legal term of art with a precise and narrow meaning, and the witness cannot reasonably answer the question without understanding the relevant law.
Since the lawyer is "arguing" his case that John Doe was driving negligently through the witness, the objection would be sustained and the improper statements stricken from the record.
If the judge sustains the argumentative objection, the lawyer may instead ask questions such as "was John Doe exceeding the posted speed limit?