Lawful versus Legal makes different meanings very clear. Yet many people think these two words mean the same.
In brief; lawful and legal differ in that ‘lawfull’ contemplates the substance of law [its content], whereas ‘legal’ alludes to the form of law [its form or appearance].
The adjective LAWFUL has 4 senses:
Conformable to or allowed by law
According to custom or rule or natural law
Authorized, sanctioned by, or in accordance with law
Having a legally established claim
Clearly #4 is the reason many people believe both lawful and legal mean the same. (see observations below)
To say an act is “lawful” implies that it is authorized, sanctioned, or at any rate not forbidden, by law. The term lawful more clearly suggests an ethical content than does the word legal.
Legal denotes compliance with technical or formal rules. To say that an act 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.”
Legal fraud is possible, but lawful fraud is a contradiction in terms. Note however that a lawful writ, warrant, or process is the same as a legal writ, warrant, or process.
Example – Lawful versus Legal
Marriage is “lawful”. That we know. Also we know that government cannot give a license or permit you to do anything that is “unlawful”.
Nonetheless government insists you have a marriage license so that your marriage is ‘legal’.
If however we can do something ‘legally’ with a license, we can do the same thing ‘lawfully’ without one.
‘Lawful’ speaks of freedom while ‘legal’ speaks of being bound.