Lawful

 

“Conformable to law : allowed or permitted by law : enforceable in a court of law : Legitimate; constituted, authorized, or established by law.”

 

Source:  Webster’s Third New International Dictionary

 

“Legal, warranted or authorized by the law; having the qualifications prescribed by law; not contrary to nor forbidden by the law; not illegal.

           

The principal distinction between the terms ‘lawful’ and ‘legal’ is that the former contemplates the substance of law, the latter the form of law. To say of an act that it is ‘lawful’ implies that it is authorized, sanctioned, or at any rate not forbidden, by law. To say that it is ‘legal’ implies that it is done or performed in accordance  with the forms and usages of law, or in a technical manner. In this sense ‘illegal’ approaches the meaning of ‘invalid.’”

 

Source:  Black’s Law Dictionary, 6^th Edition