Like one’s rights in the use of Roman numerals (5)

I believe the answer is:

civil

'like one's rights' is the definition.
(as in civil rights)

I cannot understand how the rest of the clue works.

(Other definitions for civil that I've seen before include "Courteously polite" , "Urbane" , "Not rude" , "Nonviolent refusal to obey laws" , "Polite and non-military" .)

I've seen this clue in the Evening Standard.

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