I couldn't find it in the book. When do you draw Long Arm of the Law cards?

I figured you'd do it every time you reveal a new train car. Is that right?

Or do the High Noon cards tell you to draw Long Arm cards?

When you reveal a tile, it has printed on the tile how many Long Arm cards to flip and resolve.

Having not seen the full High Noon deck, that might be an additional source of Long Arm cards.