Is anyone a little more versed in US law able to explain what kind of precedent this sets for further cases in Iowa or I'm guessing to be nation wide due to the judge being federal?
(In what follows, I'll be making some generalizations or slight simplifications. There may be exceptions here and there to some things I say, but it should be good enough to explain how precedent works).
There are three levels of federal courts. At the bottom level, there are the district courts. These are what most people think of when they think "court". These courts hold trials to determine what the facts are, and they apply the law to those facts. This generally also involves interpreting the meaning of the law. The district courts are were jury trials are held (although the parties can agree to have a judge determine the facts instead of a jury).
Next level up are the appellate courts. If a party does not like the outcome of a district court trial or of a decision a district judge makes, they can appeal to an appellate court. The appellate court does not concern itself with determining the facts of the case--it accepts the findings of the district court there [1]. The appellate court concerns itself with whether or not the district court correctly determined what law applies to the case, correctly interpreted that law, correctly applied it, did not allow evidence that should have been excluded, did not exclude evidence that should have been allowed, and things like that.
Finally, at the top level, we have the Supreme Court. They handle appeals from parties dissatisfied with appellate court rulings. Generally, the Supreme Court gets to decide whether or not it will hear an appeal. It generally only takes cases where there is some important point of law to be settled, or where different appellate courts have been reaching contradictory conclusions and a nationwide standard needs to be imposed.
There is a single Supreme Court.
There are 12 general appellate courts (and there are some specialized appellate courts that only deal with specific legal areas, and are not relevant for this discussion), each handling a particular geographical area. These are called Circuits. The full name of these courts are "U.S. Court of Appeals for the (whatever) Circuit". These courts each have many judges (for instance, the 9th Circuit, which covers the Western US, has 29 judges), with courtrooms at many places in the Circuit. When the Court of Appeals hears an appeal, it will be handled by a panel of judges, generally three. For more important cases, they will have larger panels.
There are around 700 federal district courts.
Precedent goes downward, along the same lines that appeals go up on. The Supreme Court sets binding precedent for all of the Courts of Appeal and for all of the district courts. The Court of Appeals for a given circuit sets binding precedent for the district courts in its geographical region. District courts do not set binding precedent.
Note I said "binding" precedent. That is precedent that must be followed. There is also non-binding precedent (also called persuasive precedent, and a few other names). For instance, if a federal appeals court in New York makes a ruling on some legal question that no other circuit has dealt with, and then later a district court in California deals with that same question, the California court does not have to follow the New York court, even though the New York court is at a higher level, because the New York court is in a different circuit--the New York decision is not binding precedent. The California court will, however, look to the New York court's opinion for guidance.
In this particular case, the ruling was by a district court, so pretty much means nothing as far as precedent goes. That particular district court will probably rule the same way on future cases it sees that have substantially the same fact pattern, and other district courts in the same circuit will look at its reasoning and take it as non-binding precedent, but won't be bound to follow it.
[1] This is not quite correct. I think they can overrule the jury on a matter of fact if they determine that no reasonable jury could have reached that conclusion.
