A question regarding a clan badge

[MacMillan of Rathdown]

I would be curious what kilts thescot wears this badge with? If for instance with the Leatherneck tartan, one might expect it to be USMC related;

most people can not recognize any tartan but their own-- they honestly wouldn't know the difference between Leatherneck and Lamont. Those who know something of heraldry would see the badge and think "armiger", without regard for the clan/tartan connection.

...if with a clan tartan then I would take your point, though I would hope any gentleman who had possible exception to it would take the time to discern that it was in fact no way clan related (other than US Marines being a rather clannish group) and thus that no disrepect was intended.

Some might inquire, but the vast majority would not. I think most people would arch an eyebrow, and shrug. A few might say, "ooh", and that would be about it.

A related question, as I know little of heraldry. Would one be guilty of anything other than poor taste and disrespect of tradition if they were to wear a plain circlet cap badge or use another's arms in the US? I gather that there are some criminal or civil penalties for doing so in Scotland? Please note that I have no intentions of doing so, in fact I own neither bonnet nor badge, but am just curious if there is any protection for heraldic items from other nations in the US.

In the USA the use of another person's arms would probably be the legal equivalent of putting a Mercedes Benz star on a kit car, although it would be up to the aggrieved armiger to seek redress through the civil courts. The armiger might have recourse through the criminal courts as he could conceivably claim "identity theft", but I think that would be a bit of a reach.

As the Scottish courts have no jurisdiction in the USA, I doubt someone passing themselves off as an armiger could expect a call from the Procurtor Fiscal of the Court of the Lord Lyon. As an aside, in Scotland foreign armigers, unless resident in Scotland, are exempt for the jurisdiction of Lyon Court. Once they take up residence then they are expected to register their arms and follow Scots law as it appertains to the use of heraldry.