Why might knowing the detailed arguments in “The Federalist Papers” be so important for lawyers appearing before Chief Justice John Roberts’ Supreme Court?
The Roberts Court, I believe, will be remembered in history for a few things. First, it will be remembered as a very friendly court towards the power of the federal government. Second, it will be remembered as business-friendly. Lastly, it will be remembered as a more strict constructionist court, as others have mentioned, in terms of the Framer's original intent in writing and phrasing the Constitution. That is, if the 5-4 balance of the Supreme Court does not change in a possible Obama second term.
If the legal leanings of the judge(s) are well known ahead of time, referencing the Federalist Papers may help to make or reinforce a legal argument presented by an arguing attorney. On the other hand, arguing counter to the Papers may be the way to reinforce an argument if the target judge(s) are opposed to the reasoning in the Papers.
Yes, this is a rather broad question, but the answer to it lies in the different perspectives of various judges to the constitution as a document, and how we approach and interpret it as a document in today's radically different context. This indicates the importance of the Federalist Papers as it helps us to understand the original constitution and its background which is of course of great importance to its interpretation today.
There is a lot of variety there, so it would depend on the specific argument. However while some judges believe that the Constitution is a living document, others want to peer into the brains of them men who wrote it. The closest thing we have to that is the Federalist Papers, because they were actually written by Founding Fathers and, unlike the Constitution, go into detail explaining rationale and opinions.
When the constitution was originally written, the language used was deliberately vague; there was no other way to get a majority of the delegates to pass. A good example of its ambiguity is the language:
In Case of the Removal of the President from Office, or of his Death, Resignation, or Inability to discharge the Powers and Duties of the said Office, the Same shall devolve on the Vice President.
What exactly does that mean? When William Henry Harrison died in office, (the first President to do so) there was some issue as to whether his Vice President would in fact become President, was simply acting president, or remained Vice President with the powers of the Presidency. This issue has of course been cleared up by Constitutional Amendment; but there are others equally vague.
Normally, Courts rely on precedent (previously decided cases) to determine their rulings. In the case of the Supreme Court in which its primary function is to interpret the Constitution, it is necessary that they be able to ascertain the intent of those who wrote the Constitution to determine its true meaning. Even this, of course, is subject to interpretation.
The supreme irony in all of this is that a number of the Federalist Papers were written by Alexander Hamilton, who was not present for a great deal of the debate on the Constitution. He had been a delegate from New York, but that delegation walked out in protest, and he was obliged to leave with them. So much of the Federalist Papers can only aim at the true intent of those present.
Chief Justice Roberts (and others like Justice Scalia) believe in the idea of "original intent." Original intent is the idea that cases relating to the Constitution should be decided on the basis of what the Framers of the Constitution intended the document to mean. In other words, cases should be decided based on the intent of the Framers, not what we think today.
The intent of the Framers can, to some, be found in writings like The Federalist. In those papers, some of the Framers explained what they were thinking when they wrote the Constitution. The papers give an insight into the thinking of those particular Framers.
Because of this, a lawyer might do well to refer to these documents. Such references might persuade the Court that the lawyer's position is consistent with that of the Framers.