Read 36 USC Section 301.
It’s actually codified law that you put your hand over your heart.
Unenforceable, as there are no penalties associated, but, it is federal law.
https://www.law.cornell.edu/uscode/text/36/301
It’s actually codified law that you put your hand over your heart.
I stand corrected. But I've seen it disregarded so routinely (probably because nobody even knows it's federal law) that it's certainly not a sign of disrespect.
Additionally, such a law appears to be obviously unconstitutional as it essentially mandates specific speech (expression).
Vote Trump!