linch, lynch

Linch or linch descibes a kind of hardware. A linchpin is the smooth bolt that holds the two pieces of a hinge together--
He is trying to hang a door, but the linchpin won't go in.
This linchpin got bent when we took off the door; we'll need a new hinge.
Linch or linch also means a ledge or right-angled projection--
You can hang the sign right above the brick linch on the front wall.

Lynch or lynch means to hang a person as a vigilante mob--
The sheriff had to protect the accused from a lynch mob.
Criminals were once hanged in the United States, but a lynch mob was illegal, because the accused had not been tried and convicted.

Now that you know that, you can say--
"The marshal believed that trial by jury was the linchpin that held society together, and so opposed the lynch mob and vigilante justice."

Note--"lynch"also  means a strip of unplowed land between two fields--
The daisies growing in the lynch make everything look cheerful.