How was the "unwritten law" of lynching supported by written law?

 boldly avowed their purpose to intimidate, suppress, and nullify the Negro's right to vote. ... Thus lynchings began in the South, rapidly spreading into the various states until the national law was nullified and the reign of the “unwritten law” was supreme.

Explanation:

the roman army grew in size and became dominant in the mediterranean region.

i think the answer is a and i hope this ; ))