not relating to, involving, or following the rules of a country's constitution (= the set of political principles by which it is governed)

Cases should be decided on nonconstitutional grounds wherever possible.

An individual can lose his or her non-constitutional right to a lawyer by failing to take timely steps to obtain one. 如果没有及时设法找到律师，个人可能会失去其获得律师的非宪法权利。