Here's a couple of excellent references for you, if you'd like to dig deeper than I will be:

• Federal Rulemaking, the federal judiciary's website on the federal rules of practice, procedure, and evidence. There you'll find a wealth of information, including proposed changes to the rules of evidence, at the bottom of that page.

• And, as always, Harvard has a very thorough collection of materials on various shadings of the topic, including cases that bear on the subject, problems selected to get law students to think about the application of the rules to specific fact situations, and articles and treatises on the subject.

THE DIFFICULTY ABOUT NEGATION

Consider, for example, a case in which it is common ground that 499 people paid for admission to a rodeo, and that 1,000 are counted on the seats, of whom A is one. Suppose no tickets were issued and there can be no testimony as to whether A paid for admission or climbed over the fence. So by any plausible criterion of mathematical probability there is a .501 probability, on the admitted facts, that he did not pay. The mathematicist theory would apparently imply that in such circumstances the rodeo organizers are entitled to judgement against A for the admission-money, since the balance of probability (and also the difference between prior and posterior probabilities) would lie in their favour. But it seems manifestly unjust that A should lose his case when there is an agreed mathematical probability of as high as .499 that he in fact paid for admission.

Indeed, if the organizers were really entitled to judgement against A, they would presumably be equally entitled to judgement against each person in the same situation as A. So they might conceivably be entitled to recover 1,000 admission-moneys, when it was admitted that 499 had actually been paid. The absurd injustice of this suffices to show that there is something wrong somewhere. But where?...

My job, though, is to go in the opposite direction, to simplify, so that those of us who are not lawyers or law students or professors can at least get the big picture, and then any who wish to can go off and dig deeper to their heart's content, which is how so many of you have ended up going to law school after reading Groklaw.

To start to grasp the big picture by taking our first baby steps, you need to know that in the US, every state has its own laws. If a lawyer moves from Minnesota to California, he has to not only get permission to practice in the new state, he has to study so he knows how. I remember an interview with an attorney, whose name I've forgotten, who told about finding himself in court on his first case in a new state. He hadn't had time to really get conversant with the new state's laws, so he was bungling the job. What do you even ask a witness, if you don't know what you need to prove to meet the law's requirements? The judge first tried to send him hints on what he needed to ask and finally lectured him, explaining to him in front of everyone what the elements were he needed to prove in the case under that state's law and telling him to go home and study before he appeared in his courtroom again. It was humiliating, I'm sure, and no doubt he cracked the books after that.

It's the same for paralegals too, by the way, which his why they hate to move out-of-state, because they know they'll have to study everything all over again and then try not to get confused. Laws inside a state change all the time too, of course, and you have to keep up with all the various courts' rules, which change too, and the judge's preferences -- and on the state level, the judges change all the time, too -- so anyone who becomes a lawyer or any kind of legal support staff accepts a lifetime of studying. Of course, some of us think there's not much better in life than to learn new things, so that's the type of person who should gravitate to the legal world. If you are a programmer, you can relate, because you are always having to learn new languages and develop new skills, aren't you?

In contrast, though, if you're an engineer, you can go anywhere, in any state, and Ruby doesn't change, or C++, or Visual Basic or Perl. What you've learned still works, assuming it's still in demand. A doctor, if he moves, has to get accredited in the new place, and while in some cases that involves study and always involves a lot of paperwork, at least the human body stays the same, wherever he goes. The law doesn't.

But there is one thing that lawyers probably won't have to spend a lot of time on if they move, and that's the rules of evidence. That's because they're very much the same no matter where you go, and what they are all like are the Federal Rules of Evidence. Why would that be true?

I think it's because the federal rules have been worked out over time, are meant to be applicable in all the states when you are in the federal court system, and they are designed to be fair. Humans often agree on the big picture when it comes to fairness, and in this case, they seem to, despite the complexity of the rules. In fact, some states just use the federal rules and call them their own, as the introduction to Cornell University's Federal Rules of Evidence section points out:

These rules govern the introduction of evidence in proceedings, both civil and criminal, in Federal courts. While they do not apply to suits in state courts, the rules of many states have been closely modeled on these provisions.

That's the overview, and you are welcome to read all the rules, if you are the type that likes the long answer first and right away. You'll find the rules for experts there, and on depositions. You'll see that under each section, you'll find a link marked "Notes," which will explain a bit about that section and what its purpose is. The Notes are very helpful if legalese isn't your mother tongue.

If you read the section Article IX, Miscellaneous Rules, you'll find that the Federal Rules of Evidence apply pretty much everywhere, in all the district courts, the US courts of appeal, even in bankruptcy court, pretty much in all the federal courts except where there are different rules specifically set up, such as for proceedings before a grand jury or an extradition hearing or in criminal law in misdemeanor matters, bail hearings, things like that. You can read the list. Magistrate judges are bound by the same rules of evidence in civil cases, but not when handling misdemeanors and other petty criminal matters. Remember at one of the last hearings in SCO v. IBM when Magistrate Judge Brooke Wells mentioned that she couldn't do a hearing on a particular day because she was scheduled for the criminal part that week? That's the other thing magistrate judges do.

They list where the Federal Rules of Evidence apply very explicitly, so everyone knows the rules of the road at the beginning. So if you are sued in the District Court of Guam, you know what the evidentiary rules are. The whole idea of a fair justice system is that no one gets surprised or ambushed. You will note, if you read the list, that there is an exception regarding admissibility, and that's for Rule 104, Preliminary Questions:

Rule 104. Preliminary Questions

(a) Questions of admissibility generally.

Preliminary questions concerning the qualification of a person to be a witness, the existence of a privilege, or the admissibility of evidence shall be determined by the court, subject to the provisions of subdivision (b). In making its determination it is not bound by the rules of evidence except those with respect to privileges.

(b) Relevancy conditioned on fact.

When the relevancy of evidence depends upon the fulfillment of a condition of fact, the court shall admit it upon, or subject to, the introduction of evidence sufficient to support a finding of the fulfillment of the condition.

(c) Hearing of jury.

Hearings on the admissibility of confessions shall in all cases be conducted out of the hearing of the jury. Hearings on other preliminary matters shall be so conducted when the interests of justice require, or when an accused is a witness and so requests.

(d) Testimony by accused.

The accused does not, by testifying upon a preliminary matter, become subject to cross-examination as to other issues in the case.

(e) Weight and credibility.

This rule does not limit the right of a party to introduce before the jury evidence relevant to weight or credibility.

This makes sense, if you think about it, because you want the judge to be free to look at everything pertinent when trying to decide if a witness qualifies or whether there is a privilege properly asserted. Privilege is like attorney-client privilege, or journalistic privilege, or doctor-patient. The point is to keep the jury from hearing things it shouldn't -- the jury only hears what the judge decides it can hear, after that evaluation -- so the judge hears a lot more than the jury does. That's fair because the judge knows the law very well, where the jury doesn't. That's also why the judge can read whatever he wishes, and juries are sometimes told not to read about the case they are working on. They might be influenced by media FUD, where a judge isn't going to be. So, the jury hears only what the judge rules it can hear. And did you notice that part about privilege? While the judge is not bound by the rules of evidence in determining whether a privilege exists, once that determination is reached, privilege, such as the attorney-client privilege, is respected, and the rule on that is totally clear, Rule 1101(c), Rule of Privilege:

The rule with respect to privileges applies at all stages of all actions, cases, and proceedings.

That's the rule that SCO just relearned.

Now, we know each other pretty well by now. You know my little quirks and flaws, and I know you too, and I'm pretty sure that many of you are asking the following questions: Why does it have to be so complicated? Why even have rules of evidence? Why can't a witness just sit down in the witness chair and simply tell what he knows? Because what a witness actually knows first-hand and what he thinks he knows because he heard something from somebody might not be identical. The law is interested in hearing the former, but not the latter, as a rule. And because, sad to say, sometimes witnesses lie. The whole point is to try to keep proceedings fair despite all that, as Rule 102 states:

Rule 102. Purpose and Construction

These rules shall be construed to secure fairness in administration, elimination of unjustifiable expense and delay, and promotion of growth and development of the law of evidence to the end that the truth may be ascertained and proceedings justly determined.

Did you notice how the law itself recognizes that the law must grow and develop? But the underlying principles have traditionally stayed the same. It's just how to apply the principles fairly that can be fine-tuned. In an article on privileges, Commentary: Privileges in General, again linked to on the Harvard page, the authors explain it this way:

In Chapter II we explored the fundamental rule of evidence that all relevant evidence is admissible and all irrelevant evidence is inadmissible. The premise on which this primary rule is based is that accurate fact-finding in an adversary system of justice is promoted when the factfinder has all the information that bears on the issues in dispute. As we have seen, there are many exceptions to the primary rule. But virtually all the exceptions we have examined to this point have been justified on the grounds that the excluded evidence is likely to undermine the fact-finding process because of the unreliability or prejudicial nature of the evidence or its capacity to mislead or confuse the factfinder.

Now, one unique aspect of the US legal system, as it was originally set up, was that it was designed by folks who came to this country after having been abused legally elsewhere. Shakespeare had relatives killed for being in the wrong group. Some were religiously oppressed or suffered terribly after falling into debt, and when they set up the new US legal system, it was all designed to protect the little guy, the unpopular, the powerless, the underdog, because that is what they had been in the countries they came from.

The plain fact is that you will write a law differently when you've been victimized than if you've lived always as a privileged member of the power elite. The latter tend to write laws so as to punish severely those that don't do what they're told, with an emphasis on strict enforcement at all costs. The former write laws with the thought in their minds, "What if this law were applied to me or my relatives?" It tends to result in more compassionate, careful laws. That was the original idea, to protect the least popular man, the religion everyone hated, to protect against mob justice running wild against those not in power, those without a friend in the world.

When you read the Constitution and the Bill of Rights, you can see that point of view throughout. It came from having been written by those who had been in the least popular group or were a member of an outlawed religion. Don't forget, at one time in Europe you could be tortured and even burned to death for translating the Bible or just for not believing the current dominant religion's teachings. So when people came to what became the United States, they had some definite ideas on what would work better than that.

And you see that in the Federal Rules of Evidence too. You can't be convicted on hearsay evidence, for example. Now the rules regarding hearsay are complicated, but the overview is that a liar or a bunch of gossips shouldn't be allowed to destroy your life. Someone has to have seen you do the unlawful thing and be willing to testify to it in court, and be subject to cross examination as to the truthfulness and accuracy of the testimony. (Hearsay is not admissable, with some exceptions, and here's what isn't hearsay.) He can't come in to court and tell the court that his brother saw it. The brother himself has to show up, and if he can't make it to court or won't testify, and there's no other evidence on that point so the defendant goes free as a result, the US legal system will let that happen, because it is a fundamental of this system, or originally was, that it's better for a guilty person to walk free than for an innocent man to be wrongly punished.

It's beautiful, if you think about it, isn't it? It's a system designed to protect the wrongly accused and the underdog. Anyway, I think it's beautiful, and it's one thing that drew me to the law, the essential fairness of the system as it was designed, that the designers of the system thought it really mattered to protect everyone's rights. So when it comes to evidence, the judge has the job of applying the rules so as to keep the jury from hearing inadmissable evidence, as Rule 103(c) says:

In jury cases, proceedings shall be conducted, to the extent practicable, so as to prevent inadmissible evidence from being suggested to the jury by any means, such as making statements or offers of proof or asking questions in the hearing of the jury.

In other words, there is even a rule about trying to slip in evidence by a back door. Other than that, the court will let all relevant evidence in. What does "relevant" mean here? Rules 401-403 explain:

Rule 401. Definition of "Relevant Evidence"

"Relevant evidence" means evidence having any tendency to make the existence of any fact that is of consequence to the determination of the action more probable or less probable than it would be without the evidence.

Notes

Rule 402. Relevant Evidence Generally Admissible; Irrelevant Evidence Inadmissible

All relevant evidence is admissible, except as otherwise provided by the Constitution of the United States, by Act of Congress, by these rules, or by other rules prescribed by the Supreme Court pursuant to statutory authority. Evidence which is not relevant is not admissible.

Notes

Rule 403. Exclusion of Relevant Evidence on Grounds of Prejudice, Confusion, or Waste of Time

Although relevant, evidence may be excluded if its probative value is substantially outweighed by the danger of unfair prejudice, confusion of the issues, or misleading the jury, or by considerations of undue delay, waste of time, or needless presentation of cumulative evidence.

Notes

Here's one final rule, and it is one you will probably like, Rule 301:

Rule 301. Presumptions in General Civil Actions and Proceedings

In all civil actions and proceedings not otherwise provided for by Act of Congress or by these rules, a presumption imposes on the party against whom it is directed the burden of going forward with evidence to rebut or meet the presumption, but does not shift to such party the burden of proof in the sense of the risk of nonpersuasion, which remains throughout the trial upon the party on whom it was originally cast.

That's legalese for: SCO has to prove its claims (and of course the same goes for IBM or Novell's counterclaims -- they have to prove those), and that's true at trial, not just with the judge in preliminary motions. That burden to prove its claims lies squarely on SCO's shoulders, wriggle though it may.

So there you go, an overview. We can talk about the specifics later, but at least you have enough to help you to understand why there are rules of evidence and what they are designed to accomplish.