Con l'istanza contestiamo l'infrazione.

Here con means with or by means of.

So Con l'istanza is not just physically with the document in hand. In this context, it usually means something like:

• by filing the petition/application
• through this formal request
• by means of this motion

In legal or administrative Italian, con often introduces the instrument or document used to do something.

No. Istanza is a false friend here.

In legal or administrative Italian, istanza usually means:

• application
• request
• petition
• motion
  depending on the context

So istanza is a formal request submitted to an authority, office, or court.

It does not normally mean English instance in this kind of sentence.

Italian often uses the definite article where English may not.

• la istanza becomes l'istanza because istanza begins with a vowel.
• This is just elision: la + istanza → l'istanza

So:

• con l'istanza = with the application / with the petition

Using the article here is completely normal in Italian.

Yes. Contestiamo is the 1st person plural present indicative of contestare:

• io contesto = I contest
• noi contestiamo = we contest

So contestiamo l'infrazione means:

• we contest the violation/offense
• we challenge the alleged infraction

In formal or legal language, contestare often means to dispute, to challenge, or to object to something.

In theory, it can look identical to the noi subjunctive form, which is used for let's ... in Italian.

So depending on context, contestiamo could potentially be interpreted as:

• we contest
• let's contest

However, in this sentence, the most natural reading is we contest, especially because it sounds like a formal statement in a legal/administrative context.

If it were clearly an exhortation, the surrounding context would usually make that obvious.

Infrazione means something like:

• infraction
• violation
• offense
• breach

The best translation depends on the context.

For example:

• traffic law: traffic violation
• rules/regulations: breach or violation
• administrative/legal context: infraction

So l'infrazione is the alleged violation/offense being challenged.

Because infrazione is a feminine singular noun:

• base article: la
• before a vowel: l'

So:

• la infrazione → l'infrazione

This is the same pattern as:

• l'idea
• l'acqua
• l'ora

That is the normal word order in Italian:

• subject (often omitted)
• verb
• object

Here the subject noi is omitted because the verb ending -iamo already tells you it means we.

So the structure is:

• (Noi) contestiamo l'infrazione.
• We contest the infraction.

Italian often drops subject pronouns when they are not needed.

Because Italian is a pro-drop language: the verb ending usually shows the subject clearly enough.

Here contestiamo already tells you the subject is we.

So:

• contestiamo = we contest

You could say Noi contestiamo l'infrazione, but that would usually add emphasis, contrast, or clarity.

Both are possible, but in natural English, by filing the petition/application or through this petition may sound more idiomatic, especially in a legal/administrative context.

A very literal translation is:

• With the petition, we contest the infraction.

A more natural legal-English rendering might be:

• By means of this petition, we contest the infraction.
• Through this application, we challenge the violation.
• By filing this petition, we contest the alleged infraction.

So the best choice depends on how literal or natural you want the English to be.

Yes, very much so.

Several things make it sound formal:

• istanza is bureaucratic/legal vocabulary
• contestare un'infrazione is formal/legal phrasing
• the structure is concise and administrative in tone

In everyday speech, Italians would usually choose simpler words unless they were talking about official documents, fines, legal matters, or bureaucracy.

Yes. Contestare can have different nuances depending on context, such as:

• to dispute
• to challenge
• to object to
• to criticize
• in some contexts, even to charge/allege against someone in legal language

But in contestiamo l'infrazione, the meaning is clearly we dispute/challenge the infraction.

That said, in legal Italian, contestare can sometimes mean to formally allege an offense rather than to dispute it, so context always matters. Here, because of the structure and likely intended meaning, it is understood as we contest/challenge.

Yes, mainly these three points:

1. istanza is a false friend
   It usually means application/request/petition, not instance.

2. contestare does not always map perfectly to English to contest
   In formal contexts it can mean to dispute/challenge, but in some legal settings it may have other specialized meanings.

3. Italian uses articles more often than English
   So l'istanza and l'infrazione are normal even where English might sometimes omit the in a more abstract translation.

So this sentence is short, but very typical of formal Italian bureaucracy/legal language.