In iudicio iudex reae innocentiam quaerit, non pecuniam eius.

Because in with a fixed place usually takes the ablative in Latin. Here iudicium means court or trial, and in iudicio means in court or at the trial.

So:

• in + ablative = in / on / at
• iudicio = ablative singular of iudicium

This is different from in + accusative, which often means into or shows motion toward something.

Iudex is nominative singular because it is the subject of the sentence: the judge is the person doing the action.

• iudex = judge
• quaerit = seeks / looks for / investigates

So iudex quaerit = the judge seeks/investigates.

Because reae is genitive singular, not nominative. It means of the defendant or the defendant's.

In this sentence, reae depends on innocentiam:

• reae innocentiam = the innocence of the defendant

So the sentence is not saying the defendant seeks anything. The subject is still iudex.

Rea is a feminine noun meaning female defendant, female accused person, or woman on trial.

Its forms here are:

• rea = nominative singular, the female defendant
• reae = genitive singular, of the female defendant

So reae innocentiam means the female defendant's innocence.

Because it is the direct object of quaerit.

The verb quaerere often takes a direct object meaning the thing sought, looked for, or investigated.

So:

• innocentiam quaerit = he seeks/investigates innocence
• more naturally in English here: the judge investigates the defendant's innocence

Innocentiam is accusative singular of innocentia.

Literally, quaerit means seeks, looks for, asks about, or investigates, depending on context.

In a courtroom sentence like this, a natural sense is:

• investigates
• tries to determine
• inquires into

So although the literal wording is seeks the defendant's innocence, the idea is that the judge is trying to determine whether she is innocent.

Latin often uses a genitive noun where English might use 's or a possessive pronoun.

So:

• reae innocentiam = the defendant's innocence
• literally, innocence of the defendant

This is a very common Latin structure:

• puellae liber = the girl's book
• viri gloria = the man's glory
• reae innocentia = the defendant's innocence

This is an important point.

Latin uses suus, sua, suum for a possessive that refers back to the subject of the clause. But here her money refers to the defendant, not to the subject iudex.

The subject is iudex = the judge.

So:

• pecuniam suam would mean his own money = the judge's own money
• pecuniam eius means her money (or his money), referring to someone else

Since the money belongs to the defendant, not the judge, Latin uses eius.

Eius is the genitive singular form of is, ea, id and means of him, of her, or of it.

Here it modifies pecuniam:

• pecuniam eius = her money

Even though pecuniam is accusative, eius stays in the genitive because it means of her.

This is similar to English the money of the defendant, though English usually prefers her money.

Latin word order is more flexible than English because the endings show the grammar.

This order helps with emphasis and clarity:

• In iudicio sets the scene first: in court
• iudex gives the subject: the judge
• reae innocentiam presents the main thing under investigation
• non pecuniam eius comes last as a contrast: not her money

So the ending gives a strong contrast:

• the judge seeks the defendant's innocence, not her money

Latin often places an important contrast near the end of the sentence.

Classical Latin has no articles like English the or a/an.

So a noun like iudex can mean:

• a judge
• the judge

The exact meaning depends on context. In this sentence, English naturally uses the judge and the defendant, but Latin does not need separate words for that.

Yes, Latin can move non around, but its position helps show what is being negated or contrasted.

Here:

• non pecuniam eius

means not her money. The negation is closely attached to that object phrase, creating a clear contrast with reae innocentiam.

If the sentence were arranged differently, the meaning might still be understandable, but this position makes the contrast especially neat and forceful.

Yes. They are closely related words.

• iudex = judge
• iudicium = judgment, trial, court proceeding

Both come from the same legal idea. Noticing word families like this is very helpful in Latin, because related words often appear together and reinforce each other's meaning.