Montesquieu
 

XXVI.19 That one must not decide by civil laws things that must be decided by domestic laws

The law of the Visigoths requi­red sla­ves to bind the man and woman they caught in adul­tery, and to pre­sent them to the hus­band and to the judge1 : a fear­some law, which pla­ced the enfor­ce­ment of public, domes­tic, and indi­vi­dual ven­geance in the hands of those base­born per­sons !

This law would be good only in Oriental sera­glios, where the slave who is in charge of the harem is at fault the moment there is a fault. He arrests the cri­mi­nals less to have them jud­ged than to have him­self jud­ged, and obtain from an inquiry into the cir­cum­stan­ces of the act whe­ther the sus­pi­cion of his negli­gence can be over­loo­ked.

But in coun­tries where the women are not guar­ded, it is mad for the civil law to sub­ject them, who govern the house, to inqui­si­tion by their sla­ves.

That inqui­si­tion could be, in cer­tain cases at the very most, an indi­vi­dual domes­tic law, and never a civil law.

Lex Visigothorum, book III, tit. 4, §6.