Ruer dans les brancards

Imagine a mischievous donkey named Pierre in a French countryside village. Pierre, with a sly twinkle in his eye, decides one day that he's had enough of pulling carts.  He starts kicking and bucking, refusing to budge. What he is doing is "ruer dans les brancards," or "kicking against the traces," making it clear that he's not going to follow the routine anymore.

Similar to the English expression, ruer dans les brancards can be used metaphorically to describe someone who rebels or resists authority, rules, or constraints, often in a defiant and loud manner.

Ruer translates into kicking or bucking.  But what is a bit puzzling about the French expression, is that the term brancards refers to the stretchers employed by paramedics for transporting patients.  So, the question arises: Who is doing the kicking? Are patients kicking the nurses, or is it the other way around?

Origin

Well, neither of them.  In the 15th century, before taking on the meaning we associate with them today, brancards were two long pieces of wood extending forward from the box of a carriage, between which an equine was placed to move the load that its master needed to transport.

The phrase originally described the behavior of a horse that, when harnessed to a cart, would resist and (literally) kick against the traces, creating a challenging and difficult situation for the person trying to control the animal.

Over time, like its English equivalent, the expression started to be used figuratively to describe human behavior. It came to represent a person's outward resistance, rebellion, or defiance against rules, authority, or established norms, much like our donkey Pierre.

Examples

Les enfants ont commencé à ruer dans les brancards lorsque leurs parents ont annoncé qu'ils déménageraient dans une nouvelle ville.
The children started to rebel when their parents announced they would be moving to a new city.

Les membres de l'opposition ont commencé à ruer dans les brancards après l'annonce du nouveau projet de loi. 
The members of the opposition began to kick against the traces after the announcement of the new bill.