In Barton v Armstrong, what justified the civil law action against Armstrong?

The civil law action against Armstrong in Barton v Armstrong was justified primarily due to the threats made to Barton and his family. In this case, Barton was coerced into entering a business arrangement with Armstrong because of the fear instilled by Armstrong's threats, which had a significant impact on Barton's decision-making. The law recognizes that consent obtained through intimidation or threat is not valid, making any resulting agreement voidable by the victim.

The presence of threats signifies that Barton did not enter into the arrangement freely or willingly, thus affirming the basis for the civil action. This situation underscores the importance of genuine consent in contractual agreements, where any form of duress can invalidate the legitimacy of the contract.

While the other options may relate to issues in business practices or personal interactions, they do not directly address the crux of the legal challenge in this case, making the justification for the action against Armstrong centered on the threats made.