My father was refused a visa to visit my brother and his newborn son, my father's grandchild, based on not having enough ties to this country of citizenship (Iran). He would like to contest this as he has travelled to the USA and to many European countries and he never overstayed his tourist/visit visa.
Is there some sort of human rights law that we can mention in the appeal letter on the basis of being deprived from seeing his son and his new grandchild?