Iudex reo poenam severam dat, quia mendacium dixit.

Yes:

• Iudex — nominative singular; the subject of dat
• reo — dative singular of reus; the indirect object
• poenam — accusative singular of poena; the direct object
• severam — accusative singular feminine of severus, -a, -um; it modifies poenam
• dat — 3rd person singular present active indicative of dare; gives
• quia — conjunction meaning because
• mendacium — accusative singular; direct object of dixit
• dixit — 3rd person singular perfect active indicative of dicere; said / told

So the structure is:

subject + indirect object + direct object + verb + because-clause

Because iudex is in the nominative case, which is the normal case for the subject of a finite verb.

Also, dat is 3rd person singular, so it needs a singular subject, and iudex fits that perfectly.

A learner might expect a subject to end in -us, but Latin subjects do not have to. Iudex is a third-declension noun, and third-declension nominatives can have many different endings.

Its dictionary form is iudex, iudicis.

Because dare usually takes:

• an accusative for the thing given
• a dative for the person receiving it

So in this sentence:

• poenam = the thing given
• reo = the person to whom it is given

That is why Latin uses reo, not reum.

You can think of it as:

The judge gives a severe punishment to the defendant.

Because poenam is the direct object of dat, and severam is an adjective modifying poenam.

In Latin, adjectives must agree with the nouns they describe in:

• gender
• number
• case

So:

• poenam = accusative singular feminine
• severam = accusative singular feminine

They match because they belong together: poenam severam.

No. Latin word order is much more flexible than English word order because the endings show the grammatical relationships.

So all of these would still be understandable Latin:

• poenam severam
• severam poenam

And even the larger sentence could be rearranged in different ways.

However, word order can affect emphasis or style, even when the basic meaning stays the same.

Because Latin relies much more on case endings than on position.

In English, word order usually tells you who is doing what. In Latin, endings often do that job instead.

So in this sentence:

• Iudex is clearly the subject because it is nominative
• reo is clearly dative
• poenam is clearly accusative

That means the writer has more freedom to arrange the words.

Latin often places the verb later in the sentence, and it often puts related ideas in an order that sounds natural in Latin rather than in English.

Dat is present active indicative, 3rd person singular, from dare.

Its basic meaning is gives.

Depending on context, an English translation might use:

• gives
• is giving
• sometimes a more idiomatic expression such as imposes

But grammatically, it is simply a present tense verb.

Dixit is perfect active indicative, 3rd person singular, from dicere.

The Latin perfect often translates as:

• said
• has said
• sometimes told

Here it refers to something completed before the judge gives the punishment. The lie was told first; the punishment comes as a result. So the tense difference makes good sense:

• dat — present action in the main clause
• dixit — completed past action in the reason clause

Because that is a normal Latin way to express the idea.

Literally, mendacium dixit is something like said a lie. In natural English, we usually say told a lie instead.

So this is a good example of where you should not translate word-for-word too mechanically. The Latin grammar is straightforward:

• mendacium is the direct object
• dixit is the verb

But the best English idiom is told a lie.

Because Latin very often leaves subject pronouns unstated when the verb ending already shows the person and number.

The ending -it in dixit tells you that the subject is:

• third person
• singular

So Latin does not need to add he, she, or it unless the writer wants extra emphasis or clarity.

This is very normal in Latin.

Most naturally, it is understood from context to be the defendant — the person referred to by reo.

So the sense is:

the judge gives the defendant a severe punishment because the defendant told a lie.

However, strictly speaking, the verb dixit only tells us someone singular did it. Latin often expects the reader to infer the subject from context.

If the writer wanted to make it more explicit, Latin could repeat the noun or use a pronoun.

Quia introduces a causal clause — a clause giving the reason.

So:

• main clause: Iudex reo poenam severam dat
• reason clause: quia mendacium dixit

It connects the two ideas as:

The judge gives the defendant a severe punishment, because he told a lie.

This is a very common and useful conjunction in Latin.

Yes, within limits.

Because the cases mark the roles, several word orders could still mean essentially the same thing, for example:

• Iudex poenam severam reo dat, quia mendacium dixit.
• Reo iudex poenam severam dat, quia mendacium dixit.

The endings still show:

• iudex = subject
• reo = indirect object
• poenam = direct object

So the core meaning stays the same.

But not every rearrangement sounds equally natural, and different orders can put emphasis on different words.