Insumisión

Insumisión
 

It means nocompliance, but it is a legal term for a specific kind fo crime. I suspect it means the act of being a military deserter. Am I correct?

Correct.

As to the military deserter, I don't think it is correct, although it could be taken as such...

As a legal term, it means that you are not renouncing to your venue and the jurisdiction in which you should be tried. (insumisión)

Also, "insumisión legal" in Spain means that certain autonomic communities refuse to apply laws that should be enforced all over the country.

Allthough chileno an Angelica are correct, in this case depends on the context.

In Spain, "la insumisión", "el movimiento insumiso" and "Los insumisos" refers usually to avoiding/not going/not willing to do the military service.
A military deserter is "un desertor" and it's another case.
With other context, as already stated, refers not to obey an order or not willing to be member of an organization.

best regards :D

In that case in Chile we call them "remisos".