Analogies

The text book defines reasoning by analogy as a comparison if it is part of an argument. If one side of the comparison draws a conclusion, the other side will conclude with the same. Analogies in the law is something I felt that should have been discussed in detail. One of the example introduced in the text book questions whether or not taxes apply to Internet purchases since mail-order purchases are taxed. This subject seems to be a little confusing, because of the variations of Grey areas when such legislative examples are discussed. The basis behind legal reasoning is reasoning by example. If this is the case, how do you reason with the fact that judges may rule differently depending on how the judge interprets an issue or a law? The book finally lists that even though judges may hold different rulings for similar cases, there are still differences between each individual case which will set it apart from a previous case.