Why does Mr. Uterrson feel a terror for the law and police officers in The Strange Case of Dr. Jekyll and Mr. Hyde?
In Robert Louis Stevenson's novel, The Strange Case of Dr. Jekyll and Mr. Hyde, Mr. Utterson does not feel a terror toward the law and officers. It is Mr. Hyde, Dr. Jekyll's evil second persona, who feels a terror toward the law and officers.
The reason for Hyde's terror is that he horribly murdered Sir Danvers and, if caught by the police or turned in to the police by even his own servants (Dr. Jekyll's servants), he will be directly hung on the gallows because the murder was witnessed ("overlooked"). In the 19th century there was little or no delay between then conviction of a hanging offense (murder) and the hanging, as Dickens illustrates in his book Oliver Twist.
Mr. Utterson displays a prudent (wise) caution regarding the law and police officers--but not a terror--when he and Poole break into Jekyll's experiment cabinet because Utterson doesn't know what they will find inside.
As it turns out, they find evidence of the possibility of Jekyll's having murdered Mr. Hyde. Utterson wants to proceed cautiously so as not to involve Jekyll in any scandal or greater trouble, as Utterson says in Chapter 8,, "O, we must be careful. I foresee that we may yet involve your master in some dire catastrophe."