Ignorantia legis neminem excusat.
(Legal)

Ignorance of the law excuses no one.

(pron = ig-noh-RAHN-tee-ah LAY-ghis NEH-mih-nehm eks-KOO-saht)

Comment: I heard this a lot when I was growing up, especially after I began to
drive. One day while riding with my cousin on a rainy afternoon, his
application of the breaks resulted in very little slowing down on the wet
street. We shot through the intersection and smashed into another car.
Fortunately, no one was hurt beyond bruises. Two cars were totaled.

My father and my cousin's father, brothers, had plenty to say, and while we had
broken no "laws" this saying was quoted more than once in the aftermath. What
my father wanted me to know, as I defended my cousin's driving, is that
"everyone knows that when it's raining you cannot drive the speed limit!" The
speed limit on that street had been 40 MPH, and that's pretty much what my
cousin was doing when we slid through the stop sign.

Laws, both those on the books and those that "everybody knows" (except for 16
year olds)in their best light serve the common good. "Everybody knows" because
everyone has a stake in being safe (road rules), or in building infrastructure
and maintaining services (tax laws), or in protecting the vulnerable (child
protective services, immigration laws, descrimination laws).

What I don't know not only may hurt me, but it may hurt you, too. I love my
individual freedoms as a free citizen of one of the freest lands on the earth.
But, my freedom, what I know and don't know, touch your life--and yours, mine.