In some western movies, there are a lot of violent scenes. For example, a man on horseback ties and pulls an outlaw on the ground. My question is: What is the correct verb that can be used to describe the act of drawing an outlaw behind on the ground?
It's called "lassoing" — Dictionary.com
verb (used with object) lassoed, lassoing. to catch with or as with a lasso.
"He lassoed the villain and dragged him along the ground."
I would say "dragging" — M-W
verb to cause (something) to move along the ground, floor, etc., by pulling it
"The cowboy tied the outlaw up and took off on his horse, dragging the outlaw behind him."
There's not a lot of historical discussion readily available. So we can imagine that "lasso'd and dragged" would fit the style of language associated with the old West.
Or possibly just dragged, since that already implies that a tethering of some sort has occurred.
Another possibility is "drawn" which doesn't have a specific connection to the American West; but that is an old legal sense of the word in English. (see drawn and quartered http://www.britannica.com/topic/drawing-and-quartering)