Definition (許可性)
If someone is within their rights, they are acting in a way that is legally or morally permissible.
符合法律規定
I believe I am completely within my rights to ask for a full refund.
我相信我完全有權要求全額退款。
You are within your rights to request a change of teacher.
你有權要求更換老師。
He is perfectly within his rights to refuse to pay for that.
他完全有權拒絕為此付款。