В силу того, что жалобу подали поздно, её отклонили.

It means because, due to the fact that, or in view of the fact that.

In this sentence, в силу того, что introduces the reason:

• В силу того, что жалобу подали поздно, её отклонили.
• Because the complaint was filed late, it was rejected.

This expression is formal and is especially common in:

• legal language
• official documents
• bureaucratic style
• formal writing

In everyday speech, a Russian speaker would more often use:

• потому что
• так как
• из-за того, что

So this sentence sounds quite official.

You can partly understand it word by word, but in practice it is best learned as a set phrase.

Literally:

• в силу = by virtue of, because of, due to
• того = that
• что = that

But together, в силу того, что functions as a compound conjunction meaning because / due to the fact that.

So although the individual words have their own meanings, the whole phrase works as one grammatical unit introducing a clause of reason.

Because в силу того, что жалобу подали поздно is a subordinate clause giving the reason for what happened in the main clause.

Structure:

• subordinate clause of reason: В силу того, что жалобу подали поздно
• main clause: её отклонили

Russian normally separates subordinate clauses from the main clause with a comma.

Because it is the direct object of the verb подали.

The verb подать means to submit / file / hand in something. What was filed?

• жалобу = the complaint

Base form:

• жалоба = nominative singular

Accusative singular:

• жалобу

So:

• подали жалобу = filed a complaint
• жалобу подали = the complaint was filed / literally they filed the complaint

This is a very common Russian pattern: a 3rd person plural verb with no explicit subject can mean someone / they / people in a general or unspecified sense.

So:

• жалобу подали поздно literally = they filed the complaint late
• but in natural English = the complaint was filed late

Russian often uses this structure where English would prefer a passive:

• Меня спросили. = I was asked.
• Дом построили быстро. = The house was built quickly.

Here, подали does not mean a specific they. It just leaves the doer unspecified.

Because поздно is an adverb, and it describes how/when the action was done.

It modifies the verb:

• подали поздно = filed late

By contrast, поздний is an adjective and would describe a noun:

• поздняя жалоба = a late complaint

So:

• поздно = late, used with verbs
• поздний / поздняя / позднее = late, used with nouns

Её refers back to жалобу and means it.

So:

• её отклонили = they rejected it / it was rejected

Russian often allows pronouns to be omitted if the meaning is clear, but here её helps make the sentence explicit and smooth. Without it, отклонили would just mean rejected, and the listener would have to infer what was rejected from context.

So:

• её отклонили = clear and natural
• отклонили = also possible in context, but less explicit

Because the pronoun is the direct object, not the subject.

The noun жалоба is feminine:

• nominative: она = she/it
• accusative: её = her/it

In this sentence, the complaint is the thing being rejected, so it is the object:

• её отклонили = they rejected it

If жалоба were the subject, you would use она:

• Она была отклонена. = It was rejected.

For the same reason as подали: Russian often uses 3rd person plural with an unspecified subject.

• её отклонили literally = they rejected it
• natural English = it was rejected

This is especially common in formal or factual statements where the agent is not important, not known, or deliberately left unnamed.

Yes. A more explicitly passive version would be:

• В силу того, что жалоба была подана поздно, она была отклонена.

This sounds more heavy and official. Russian often prefers the active-looking indefinite-personal construction:

• жалобу подали
• её отклонили

Even though English often translates these as passives:

• was filed
• was rejected

So the original sentence is very natural in formal Russian.

Подали is perfective, and подавали is imperfective.

Here, подали is used because the sentence refers to a completed action:

• the complaint was filed
• as a completed event, and it was filed late

If you used подавали, it would suggest process, repetition, or a less bounded action, which would not fit as well here.

Similarly:

• отклонили is perfective because the rejection is treated as a completed result

This is very typical in official statements that describe completed procedural actions.

They are similar, because both can mean because. But the tone and nuance are different.

• в силу того, что = formal, official, neutral, often legal or bureaucratic
• из-за того, что = because of, often more everyday, and sometimes slightly more negative in tone

So in a legal-style sentence about a complaint being rejected, в силу того, что sounds especially appropriate.

Compare:

• В силу того, что жалобу подали поздно, её отклонили.
  Very formal, document-style.

• Из-за того, что жалобу подали поздно, её отклонили.
  Still correct, but less official.

Yes, Russian word order is flexible, although different orders can sound more or less natural depending on style and emphasis.

The original:

• В силу того, что жалобу подали поздно, её отклонили.

Possible variation:

• Её отклонили в силу того, что жалобу подали поздно.

Both are grammatical. The original puts the reason first, which is common in formal writing. The second version starts with the result and then gives the reason.

Russian often uses word order to manage emphasis and flow rather than strict grammatical roles alone.

Not especially. It sounds formal and official, like something from:

• a court decision
• an administrative notice
• a legal explanation
• a formal report

In conversation, a speaker would more likely say something like:

• Жалобу отклонили, потому что её подали поздно.
• Жалобу не приняли, потому что подали слишком поздно.

So the original sentence is natural, but mainly in formal contexts.