dairinin ga sinseisyo wo teisyutusuru ni sakidatte, ininzyou wo kakuninsuru.

に先立って means before, prior to, or in advance of.

It is a fairly formal expression, often used in:

• official procedures
• business writing
• instructions
• legal or administrative language

So 提出するに先立って is not just a casual before submitting. It has a more formal nuance like prior to submitting or before proceeding with submission.

Because this pattern uses the plain/dictionary form of the verb:

• Vる + に先立って
• N + に先立って

So:

• 提出するに先立って
• 会議に先立って

In Japanese, the dictionary form in a subordinate clause like this does not automatically mean present tense in the English sense. It can refer to an action that is going to happen later than the main action.

Here, the order is:

1. 委任状を確認する
2. 代理人が申請書を提出する

So the application has not been submitted yet at the time of the checking.

Both can mean before, but they are not identical in tone.

• 提出する前に = neutral, everyday Japanese
• 提出するに先立って = more formal, official, procedural

Compare:

• 出かける前に、ドアを閉める。
  Before going out, I close the door.
  Very normal everyday Japanese.

• 申請書を提出するに先立って、委任状を確認する。
  This sounds like an office procedure or written instruction.

Also, に先立って can carry a nuance of as a preliminary step or in preparation for something.

Here, が marks 代理人 as the subject of the subordinate clause:

• 代理人が申請書を提出する
• the representative submits the application form

Inside clauses like this, が is very common because it identifies who performs that action.

If you used は, it would sound more like:

• setting 代理人 up as the topic
• possibly creating contrast

So が is the more natural choice here for simply stating who the submitter is.

The subject of 確認する is omitted.

That is very normal in Japanese. The sentence tells us explicitly that:

• the representative submits the application form

But it does not explicitly say who:

• checks the letter of attorney

Depending on context, that could be:

• an office worker
• the organization receiving the application
• the applicant
• someone else already understood from the surrounding text

So 代理人 is clearly the subject of 提出する, but not necessarily the subject of 確認する.

It could, depending on context, but the sentence by itself does not force that reading.

Why not? Because 代理人が belongs directly to the first clause:

• 代理人が申請書を提出するに先立って

The second clause:

• 委任状を確認する

has no stated subject.

In Japanese, omitted subjects are often supplied from context, not automatically copied from the previous clause. So the sentence is best understood as:

• Before the representative submits the application form, the letter of attorney is checked / someone checks the letter of attorney.

If the writer wanted to make it very clear that the representative does the checking too, they might phrase it differently.

Because there are two different verbs, and each has its own direct object:

1. 申請書を提出する

   • 申請書 is the thing being submitted

2. 委任状を確認する

   • 委任状 is the thing being checked

So the structure is:

• 代理人が [申請書を提出する] に先立って、[委任状を確認する]。

Each verb has its own object, so having two を particles is completely normal.

先立って comes from the verb 先立つ（さきだつ）, which means to precede.

In this sentence, it appears in the て-form:

• 先立つ → 先立って

But in practice, に先立って is best learned as a set expression meaning:

• prior to
• before
• in advance of

So even though it comes from a verb, learners usually treat Vる + に先立って as a fixed grammar pattern.

Yes. The clause

• 代理人が申請書を提出するに先立って

functions as an adverbial time expression for the main clause:

• 委任状を確認する

So the overall structure is:

• Before the representative submits the application form, [someone] checks the letter of attorney.

The comma helps show that the first clause sets the timing for the main action.

委任状 is a document that gives someone authority to act on another person’s behalf.

Depending on context, it may be translated as:

• letter of attorney
• power of attorney
• authorization form
• written authorization

In administrative contexts, it is often the document that proves the 代理人 is really allowed to submit something for someone else.

So checking the 委任状 before submission makes procedural sense.

It is usually stronger than just look at.

確認する often means:

• confirm
• check
• verify
• make sure of

In a procedural or official context, it often suggests checking that something is:

• valid
• correct
• complete
• properly authorized

So here, 委任状を確認する is more like:

• verify the letter of attorney than merely
• glance at the letter of attorney

Because Japanese often omits information that is obvious from context.

With 提出する, the destination is frequently left unstated if everyone already knows it, such as:

• a government office
• a school
• a company
• a department

So 申請書を提出する can naturally mean submit the application form without saying exactly to whom.

If needed, Japanese could state it explicitly, for example:

• 申請書を役所に提出する
• submit the application form to the city office

It sounds formal and written, not very conversational.

Reasons:

• に先立って is formal
• the vocabulary is administrative/legal
• the sentence omits the subject in a way common in procedural writing

This kind of sentence would fit well in:

• office manuals
• application instructions
• government documents
• legal or administrative explanations

In everyday speech, a speaker would more likely say something like:

• 代理人が申請書を出す前に、委任状を確認します。

That is much more natural in conversation while keeping the same basic meaning.

Yes, in many contexts 出す can mean submit, but 提出する is more formal and precise.

Compare:

• 書類を出す = casual, everyday
• 書類を提出する = formal, official

Since this sentence sounds administrative, 提出する is the better fit.

So using 提出する matches the tone of:

• 申請書
• 委任状
• に先立って
• 確認する

All of those together create a very official style.