If your firm uses an application built on Anthropic's Claude API to analyze documents such as depositions, contracts, or correspondence, it is critical to understand that not all methods of sending files to Claude are covered by a Zero Data Retention agreement. The way the application is built determines whether your client's data is protected.
I. The Two Methods of Sending Documents
There are two fundamentally different ways a software application can deliver a document to Claude for analysis. Though the end result may look the same to you as the user, the underlying mechanics — and the data retention implications — are very different.
The Files API
Think of this as uploading an attachment to a cloud drive. Your document is sent to Anthropic's servers, where it is stored and can be referenced across multiple conversations over time.
Because the file persists on Anthropic's infrastructure, this method falls outside Zero Data Retention coverage.
⬤ NOT covered by ZDR
Inline via the Messages API
Instead of uploading the file for storage, the application extracts the document's text (or encodes the PDF) and sends it directly within the conversation request — similar to pasting text into a message.
Claude reads the content, responds, and nothing is retained. The data passes through and is discarded.
⬤ Covered by ZDR
II. How It Works in Practice
To make this concrete, imagine your firm's application needs to analyze a 50-page deposition transcript. Here is how each method moves the data:
The key difference: in Method A, the document lives on Anthropic's servers until it is deleted. In Method B, the content exists only for the duration of the request and is not retained afterward.
III. The Practical Tradeoff
The ZDR-eligible approach (Method B) has one practical consequence worth understanding: because the document is not stored on Anthropic's side, each time you want to ask Claude a new question about the same deposition, the application must send the full document text again.
For a well-designed application, this happens automatically and invisibly — you would not notice any difference as a user. It may result in modestly higher usage costs, as the application transmits the document content with every request. But it is the architecture that keeps your client's data within ZDR protection.
This is a design decision your developer makes when building the application. It is not something you would toggle on or off yourself.
IV. Important Caveats
ZDR Does Not Mean Zero Risk
Even under a valid ZDR agreement using eligible endpoints, Anthropic retains the right to store inputs and outputs in two narrow circumstances. These carve-outs do not make ZDR inadequate, but you should not represent to clients that Anthropic stores absolutely nothing under any circumstances. The accurate statement is that Anthropic does not retain data except in narrow, defined situations. That distinction is worth documenting.
Exception 1: Where Required by Law
If a court order, subpoena, or other legal obligation compels Anthropic to produce data, they retain the ability to do so. This is the same kind of carve-out you would find in virtually any cloud vendor or SaaS agreement — no company will contractually promise to violate a legal obligation.
Critical Clarification: This Exception Is Primarily Forward-Looking
An important question arises: if ZDR means data is discarded immediately after processing, how can Anthropic hand anything over in response to a subpoena that arrives after the fact? The answer is that, in most cases, it cannot. You cannot produce what you do not have, and that is well-established law. A party served with a subpoena or discovery request is not sanctioned for failing to produce documents it never retained or that were destroyed under a routine, good-faith retention policy that predated the obligation to preserve.
The "required by law" carve-out is therefore best understood as serving three practical functions:
What This Means for Your Risk Assessment
The forward-looking nature of this exception may provide some comfort: for past conversations that were processed and discarded under ZDR before any legal obligation arose, that data is gone. The carve-out is not a backdoor to wholesale data retention. It is a contractual mechanism that allows Anthropic to comply with legal obligations without breaching its ZDR commitments — primarily by preserving data going forward from the point a legal obligation attaches. This is a useful point to include in client disclosures when explaining how ZDR works.
Exception 2: Usage Policy Violations
Before Claude processes any request, Anthropic runs it through an automated safety screening system — essentially a content filter. If that filter determines the content violates Anthropic's usage policy, Anthropic may store both the input and the output for up to two years so it can investigate misuse, enforce its policies, and potentially report illegal activity.
Why Exception 2 Matters for Legal Practitioners
The safety filter does not know you are a prosecutor, a defense attorney, or a compliance officer working a difficult case. It responds to content patterns. If your firm handles matters involving subject matter that could trigger safety flags — child exploitation, terrorism, weapons, fraud schemes — there is a nonzero chance that legitimately submitted legal material could be flagged and retained, even under ZDR.
This does not mean you cannot use Claude for that work. It means you should factor this possibility into your risk assessment and your client disclosures, particularly for matters involving sensitive or extreme subject matter.
A Note on Safety Classifier Results
Separate from the two exceptions above, Anthropic always retains a record of the safety filter's assessment — meaning a notation such as "this request was reviewed and passed" or "this request was flagged." Importantly, this is the filter's score or classification, not the actual text of your client's document.