Federal appellate judges are typically appointed due to their association with one of the two parties and often because they have a history of rulings favoring a certain party’s ideology in lower federal or state courts. They are officially impartial but everyone working within the system recognizes there’s tilts, and the media does too. A clear example of this is that they typically time their retirement so the party that originally appointed them can replace them.
I believe in some other countries the judiciary appoints their own replacements and in that case the ideology / politics of the judicial branch may diverge more from the legislative political parties.
Second, about the structure of the courts: in the federal judiciary, there are federal district courts (roughly, where trials happen), federal circuit courts, and the Supreme Court. There federal circuit courts are courts of appeal that sit one level above the district courts. There are 13 federal circuits. There are the First through the Eleventh Circuits, as you note. There's also the U.S. Court of Appeals for the District of Columbia Circuit (the D.C. Circuit), as well as the U.S. Court of Appeals for the Federal Circuit (the Federal Circuit). That last one is extremely unhelpfully named, since they're all "federal circuits." The Federal Circuit hears certain types of cases specially designated for it to hear (for instance, patent appeals and appeals from two lower federal courts established for specialty jurisdiction). The numbered circuits and the D.C. Circuit are geography-based. If you're wondering why D.C. needs its own circuit, consider the metric fuckton of administrative rules and regulations made by the federal government. That mainly happens in D.C. It's more complicated than that, of course, because Congress will write into certain statutes that the D.C. Circuit has jurisdiction over appeals of challenges to those statutes. Other times, litigants may choose to sue an agency in one of the other regions.
Third, the 5th Circuit is unquestionably and unarguably conservatively aligned, just as the 9th Circuit used to be unquestionably and unarguably liberally/progressively aligned. The label is decided by looking at both outcomes and reasons given for those outcomes. Pick a hot political topic. Pick a legal case involving that topic in some way. It's extremely predictable how the 5th Circuit will rule. None of this is controversial. The controversy would come from taking the next step: if you say, "Well, they're mostly right." That makes you a conservative, and that enlists you in political controversy. Because as a factual matter, they have a historically fairly high reversal rate (i.e., among the 5th Circuit cases the Supreme Court grants cert. on, the 5th Circuit gets reversed ~80+% of the time), so they're not right in the sense that the Supreme Court agrees and thus their rulings are usually the law of the land.)
A better metric is the percentage of all cases. SCOTUS granting cert already indicates there's significant willingness to overturn more often than not
I wish I could find more fine-grained statistics than what I know off the top of my head is available (StatPacks from ScotusBlog, but there seems to be no aggregation of them, just individual ones for like 25 years; Empirical Scotus, but I see no data available to play with, just posts). I also wish I were better at statistics.
Aside from the other comment regarding who appointed the judges
> chosen by the currently elected president whenever seats in the court become vacant
This is incomplete, the judges are nominated by the executive but have to be confirmed by the senate
Until recently (first Obama term I think) practically speaking a judge needed 2/3 of the senate to be confirmed, therefore in practice judges had an incentive to at least appear as moderate if they wanted to get eventually promoted.
Now that they need just a simple majority this incentive is gone and, since courts have been progressively been forced by politicians to make decisions for them, it arguably is reversed since now presidents with a majority in the senate will want to propose the most partisan judge they can get through their own party and lower judges know this
So probably it'll get worse
Basically, the sitting president appoints circuit judges to a lifetime position. The judicial candidates are selected by senators from whichever state the judge is to be appointed.
Generally, a conservative president will only nominate conservative judges. The candidates will generally be even more conservative if the senators who nominated the candidates are also conservative.
Over time, court watchers can conclude how ideologically predisposed a judge is based on their opinions. Usually, judges appointed by conservative presidents tend to rule as conservatives (that is, side with Republican positions), and vice versa with judges appointed by democrats. This trend is so consistent that you can often predict the outcome of a case from the composition of judges hearing the case.
The Fifth Circuit is dominated by republican senators and has recently seen a lot of appointments filled by Donald Trump. As a result, the Fifth Circuit overwhelmingly rules more conservatively than its sister circuits.
In this case, the fifth circuit panel ruled against the EPA in favor of commercial plastic producers. This is in line with Republican goals to erode the power of administrative agencies. Nobody is surprised by this because the Fifth Circuit operates in service of the Republican Party. As we say, you don’t bite the hand that feeds you.
Nobody is even pretending that this case has any actual legal merit. Even the right wing Supreme Court is having a hard time finding a reason to uphold it.
> Nobody is surprised by this because the Fifth Circuit operates in service of the Republican Party. As we say, you don’t bite the hand that feeds you.
These judges are not necessarily being "fed" in the corrupt way that connotes. They are people operating in accordance with their nature, and they were selected carefully during their appointment, but they might very well be capable of judicial and political independence. Lifelong appointment and all.
What's still unclear to me is why the article consistently calls it "the conservative fifth circuit court" as though that is part of its name (or as though there is another nonconservative one), whereas Wikipedia uses no such phrasing that I can find. Is that an artifact of the news medium being of "the other side" and wanting to emphasise that most of the judges were chosen by a party they don't like? Or are most judges party members, or how is this label decided? And isn't the whole point of being a judge that you're impartial, are they subtly alleging the court is partial to whatever laws are made by one of the two major parties or something?
Edit: I'm not sure what this reads like to y'all but it was meant as a genuine question with what I've already figured out for anyone else who doesn't know this (probably most international visitors, I figured)