according to the rules in a constitution

There was some doubt as to whether the government were behaving constitutionally. 有人怀疑政府是否在依照宪法行事。

in a way that relates to or is caused by your general health or your character

constitutionally weak 体质虚弱

humorous She seems constitutionally unable to make decisions. 她似乎天生优柔寡断。