Testis iurat crimen falsum esse.

Because testis is the subject of the main verb iurat.

• testis = the witness
• iurat = swears

So testis is the one doing the swearing, and subjects in Latin are normally in the nominative.

Crimen is accusative singular.

That may feel surprising at first, because in English the crime/the charge looks like the subject of is false. But in Latin, after verbs like iurat when introducing an indirect statement, Latin often uses the accusative + infinitive construction.

So in:

• crimen falsum esse

the word crimen is the subject of the infinitive esse, but in this construction that subject goes into the accusative, not the nominative.

Because this is an indirect statement.

Latin usually does not say something like:

• The witness swears that the charge is false

by using a separate word for that plus a finite verb such as est. Instead, it usually uses:

• accusative + infinitive

So:

• crimen falsum esse = that the charge is false

Here esse is the infinitive to be, not the finite verb is.

Yes. This is a classic accusative-and-infinitive clause.

Structure:

• main clause: Testis iurat = The witness swears
• indirect statement: crimen falsum esse = that the charge/crime is false

This is one of the most important Latin constructions to learn, because English often uses that + finite verb, while Latin often uses accusative + infinitive instead.

Because it agrees with crimen.

• crimen is neuter singular
• therefore the adjective describing it must also be neuter singular
• so we get falsum

Also, because crimen is accusative in the indirect statement, falsum is accusative too.

So falsum is:

• neuter
• singular
• accusative

to match crimen exactly.

It is predicative.

That means it is not simply the false charge in the same way as a basic adjective-noun phrase. Instead, it is part of the idea:

• the charge to be false
• in smoother English, that the charge is false

So falsum works with esse:

• crimen falsum esse = the charge to be false

This is different from just:

• falsum crimen = a false charge

Even though the English translation may end up similar, the grammar is different.

There is no separate word for that here.

English says:

• The witness swears that the charge is false

Latin commonly expresses this by using the accusative + infinitive construction instead of a conjunction like that.

So Latin often leaves English speakers thinking, Where did that go? The answer is: it is built into the construction itself.

Because of the structure of the sentence.

The verb iurat here introduces an indirect statement. In that indirect statement:

• crimen is the subject
• esse is the infinitive verb
• falsum is the predicate adjective

So the unit is:

• crimen falsum esse = that the charge is false

If crimen were a direct object of iurat, the rest of the sentence would not fit as neatly. The infinitive esse and adjective falsum show that crimen belongs inside the indirect statement.

Yes. Latin word order is much freer than English word order.

For example, the following would still mean essentially the same thing:

• Testis crimen falsum esse iurat
• Crimen falsum esse testis iurat
• Iurat testis crimen falsum esse

Latin relies more on case endings and grammatical structure than on fixed word order.

That said, the given order is perfectly natural and easy to understand:

• Testis iurat first gives the main action,
• then crimen falsum esse gives what is being sworn.

Testis can be masculine or feminine, depending on the actual witness.

The form itself does not tell you the biological sex here. Latin often leaves that to context.

So testis can mean:

• a male witness
• a female witness

If the meaning shown to the learner uses the witness, that is a good neutral way to understand it.

Because Classical Latin has no definite article and no indefinite article.

So:

• testis can mean witness, a witness, or the witness
• crimen can mean crime, a crime, the crime, charge, the charge, depending on context

English requires articles much more often than Latin does, so when translating into English you usually have to supply them from context.

Iurat is the 3rd person singular present active indicative of iurare.

So it means:

• he/she swears
• or more generally the witness swears

Its basic form is from the first conjugation:

• iuro, iurare, iuravi, iuratum

Here it is followed by an indirect statement, which is a very common pattern with verbs of saying, thinking, knowing, perceiving, and in many contexts also swearing.

Sometimes Latin can use a clause introduced by quod, especially in later Latin or in certain styles and contexts. But in a straightforward sentence like this, the normal classical construction after iurat is the accusative + infinitive:

• crimen falsum esse

So for a learner, the most important thing is to recognize that this sentence is using the standard indirect-statement pattern.

It can depend on context.

A native English speaker may expect crimen to mean only crime, but Latin crimen often also means:

• charge
• accusation
• offense
• crime

So if the meaning shown to the learner is something like the charge is false, that is completely natural Latin.

This is a vocabulary point rather than a grammar point, but it is a very common source of confusion.

A compact analysis would be:

• crimen: accusative singular neuter noun; subject of the infinitive in indirect statement
• falsum: accusative singular neuter adjective; predicate adjective agreeing with crimen
• esse: present active infinitive of sum

Together they mean:

• that the charge is false
• literally, the charge to be false

This is exactly the kind of pattern you will see again and again in Latin.