Legal Philosophy

When the law "runs out" in the sense that the judge must decide the meaning of a vague statute when there is no convincing evidence of the legislative intent behind such law, it is said that there is "legal indeterminacy" and the judge must use his or her discretionary decision making power.

What are the opposing views between Ronald Dworkin and American Legal Realists regarding how common it is for judges to decide cases based on discretion (judicial discretion)?