The Imperial Tribunal is seen as the most important court within the Empire since it does not deal with civil matters and small-fry criminals but rather focuses on big and important cases, like political, diplomatic and internal ones. A Senator trying to betray the Empire? A foreign diplomat who committed a crime while being in Etingnun? A governor going directly against the capital's orders? Murder of a high-ranking person? All cases for the Imperial Tribunal and not a regular courthouse. As such, only certain prosecutors and defense attorneys are allowed to hold trials at the Tribunal, most of them being graduates from the Imperial Academy. Prosecutors that prosecute at the Imperial Tribunal are called Denouncers while defense attorneys are called Vindicators. Judges, on the other hand, are just called Imperial Judges. Denouncers are officials and work for the state while Vindicators need a governmental license if they want to defend at the Tribunal. Having a great reputation can make it easier to get one.
Some things that are important for a regular court still apply, like using the right evidence, interviewing witnesses and piecing the obtained information together. You also have to watch out for lying witnesses and false evidence and try to outsmart your opponent, no matter if Denouncer or Vindicator. Both are allowed to shout from time to time and to slam on desks. People love dramatic Tribunal cases.
There are some things that make cases at the Imperial Tribunal different from regular courthouses, though.
Types of cases
You could say there are three types of cases that are ranked by importance, the importance usually indicating what type of people are involved, not necessarily the crime. Normal cases only have the Imperial Judge and they are the ones to give the final verdict. These cases usually involve lower- to mid-ranking people of importance, like an officer that did a war crime, a politician breaking a crime or someone who is not highly important being accused of treason.
Cases of the second type are a bit more important and do not only have the Imperial Judge but also a jury that consists of a number of Senators which can vote for guilty or innocent and overrule the judge's verdict that way since they are higher-ranked than an Imperial Judge. This makes things a bit more complicated since Senators usually have their own head and some of them can be somewhat opportunistic - it could even be that they are involved with someone that is part of the case, like the defendant or the victim, so they might be biased (and nobody can stop them from being so). However, you can still win enough of them over to win the case, be it as Denouncer or Vindicator. Still, they could actually try to interfere with the case, like interrupting a witness interview and asking something themselves or debating the Denouncer or Vindicator if they think they are wrong. They are allowed to do that.
The last type is for cases of extreme importance, usually involving a Senator as the defendant (or victim) or something that is of national scale and so important that the Empress herself is present. There is still an Imperial Judge but their authority is completely undermined by the sheer presence of her Majesty. The Empress is the one who can give the final verdict if the judge is not sure about it or if she thinks that the judge is wrong. If she says someone is guilty, then they are found guilty. If she says someone is innocent, then they are found innocent. So, it is important to gain her benevolence and convince her, not necessarily the judge. The Empress, however, will not allow any foul play and both sides will need to be as fair as possible since the Empress usually notices if someone is trying to deceive or flatter her. Losing her benevolence is sure to make you lose, so even sly Denouncers or Vindicators have to watch out to not get on her bad side.
Both Denouncers and Vindicators have credibility they have to uphold, especially if they want to win the case. Losing credibility means that the judge, jury or Empress will lose faith in your reasoning and will be more likely to listen to your opponent instead. There are multiple ways to lose credibility, like presenting the false evidence, saying something that is false, pressuring witnesses too much or doing something else that can be seen as unprofessional. It is also possible that your opponent will try to "attack" you to sink your credibility, usually in a heated argument or battle of wits. Losing it will tank your credibility while winning can restore it while your opponent will be the one to lose credibility. In the end, having the right evidence and arguments is still the most important and you can still win if your credibility is a bit lower but it can severely reduce your chances if it drops too low. (Credibility can also be important in regular courthouses sometimes.)
One other thing that is important to remember about the Imperial Tribunal is that the defendants are usually people of higher position as well. Should they, however, be of lower standing, like a citizen who is accused of murder, this part here will not apply.
Defendants that have a good reputation can make things harder for a Denouncer and easier for a Vindicator since that reputation could potentially influence the judge and the Senate (but not the Empress), making them more willing to reach an innocent verdict if there is no surefire evidence of their guilt. You could imagine something like a noble or well-known politician who has a lot of important friends and tries to have the most positive reputation possible, someone who is acting like they have a clean slate and never did anything wrong.
This sounds like a tough nut to crack for Denouncers but they can try to do something about it - by digging up dirt on the defendant. Most people that try to act like saints in public usually have a dirty secret or two (which does not have to be the case, however). The noble politician who is all about the people and giving them better rights could secretly be affiliated with rebels or a noble could use their influence to get something done that is not possible for them. Tarnishing the reputation of an influential defendant is not the nicest thing to do and seen as dirty by some people but it is effective and can turn things around in your favor. Of course, a Vindicator could try to refute you.
There are also Denouncers that fabricate negative claims or make use of unproven rumors, especially if the defendant seems like an actually good person.