Most grammar checkers work the same way: you paste your text, it goes to a server, the server runs analysis, and suggestions come back. That works fine for a shopping list or a personal email.
For legal documents, the question is whether sending that text to a third-party server creates a problem under attorney-client privilege or confidentiality obligations.
The honest answer: it depends on your jurisdiction, your firm's policies, and the nature of the document. But the risk is real enough that some bar associations have issued guidance on it, and enough lawyers have asked about offline alternatives that it is worth explaining what the options are.
The privilege question
Attorney-client privilege protects communications between a lawyer and their client for the purpose of obtaining legal advice. One way privilege can be waived is by disclosing the communication to a third party outside the relationship.
Whether pasting a privileged document into a cloud grammar tool constitutes such disclosure is not settled law. Arguments exist on both sides. Some ethics opinions treat cloud service providers as functional agents of the firm and not third parties for privilege purposes. Others flag it as a potential waiver depending on the circumstances.
What is not ambiguous: most standard grammar tools process your text on their servers. The text leaves your device. Someone else's infrastructure handles it, however briefly.
For routine correspondence, that risk may be acceptable. For deposition summaries, case strategy memos, privileged client communications, or early-stage litigation documents, it is the kind of thing worth thinking about before you paste.
What Grammarly does with legal text
Grammarly sends every document you run through it to their servers for processing. They say they do not sell your data, which is accurate. Their privacy policy also notes they may use text to improve their AI models unless you opt out.
Their enterprise plan includes a Business Associate Agreement for healthcare clients, which helps with HIPAA compliance. They do not have a comparable offering specifically for legal privilege concerns.
The deeper issue is structural. When your text passes through Grammarly's infrastructure, you have introduced a third-party into the chain. Grammarly employees with infrastructure access can read data as part of their job. Legal process (subpoenas, discovery) can compel production of data they hold. A security incident at Grammarly means your documents are part of that incident.
None of this means Grammarly is doing anything wrong. It is just not designed for legal confidentiality requirements. They are solving a different problem.
I covered this in more detail in the Grammarly and confidential documents post if you want the full breakdown.
Other options and their limits
Microsoft Word's built-in editor. Works offline by default. Grammar checking runs locally on your machine. No text transmitted to Microsoft servers during editing. Solid choice for document drafting on a computer. Does not help when you are working on your phone.
LanguageTool. Open-source, strong privacy reputation. Their self-hosted option is genuinely offline. Their cloud version still sends text to their servers. The desktop app for local use is good. iPhone app routes through their cloud. Not ideal for mobile legal work.
Apple's built-in spell check. Works offline on every iPhone. Catches spelling errors. Does not do grammar analysis or style suggestions. Useful but limited.
Dictation review. For voice-to-text drafting, you still need a grammar pass afterward. Most voice tools also use cloud processing.
The consistent problem for mobile: almost every grammar tool that does real analysis relies on a server. That is how they achieve the quality they do. On-device AI capable of genuine grammar checking has only recently become feasible on mobile hardware.
iPhone-native offline grammar checking
This is the gap Proofed was built for.
On iPhone 15 Pro, iPhone 16, and later devices, Proofed runs grammar analysis using Apple Foundation Models, the same on-device AI framework Apple uses for system features. No server involved. No network call made. The inference runs on the device's Neural Engine.
On older iPhones (iOS 17+), it falls back to a rules-based grammar engine that handles common grammar errors, punctuation, and spelling without any AI at all. Still fully offline.
No account required. No subscription needed for core grammar checking. Nothing transmitted.
For a lawyer reviewing a draft brief in the courthouse, checking a client summary on the way to a deposition, or editing a contract at a client site with uncertain network access, that offline architecture is practically useful as well as privacy-sound.
The limitations worth knowing: no browser extension, no desktop application, no long-form document workflow. It is a mobile tool for checking text on your iPhone. If you need full document review on a computer, Word's local editor remains the better choice. Proofed fills the mobile gap.
A note for medical professionals
The same logic applies to healthcare. Standard Grammarly is not HIPAA-compliant (no BAA on individual plans). Nurses and doctors drafting notes on their phones have the same problem lawyers do: the available grammar tools that work well also send your text to a cloud.
Offline grammar checking on iPhone is not just a legal problem. It is a healthcare problem, a government contracting problem, and an NDA problem. The underlying issue is the same.
FAQ
Is Grammarly safe for legal documents?
Grammarly sends your text to their servers for processing. For routine correspondence, this is generally fine. For documents that may be covered by attorney-client privilege, confidentiality agreements, or litigation holds, it introduces a third party into the chain. Whether that creates a legal risk depends on your jurisdiction and the nature of the document. Many law firms prohibit cloud tool use for privileged materials.
Can lawyers use Grammarly?
There is no blanket prohibition. Many lawyers use Grammarly for non-privileged writing with no issue. The concern is specifically around privileged communications and confidential client documents. Check your firm's IT and ethics policies before using any cloud service for sensitive legal work.
What grammar tools work offline on iPhone for legal work?
Proofed is the only iPhone grammar app that runs entirely on-device with no server processing. iOS's built-in spell check also works offline but does limited grammar analysis. LanguageTool's self-hosted version is offline on desktop but their iPhone app uses cloud processing.
Does Microsoft Word check grammar offline?
Yes. Word's grammar and spelling checker runs locally. On a Mac or PC, it does not send your documents to Microsoft for processing during editing. The mobile Word app (iOS) has more limited offline functionality and some features may require a connection.
What about dictating and then checking?
Apple's on-device dictation (available offline on iPhone 15 Pro and later) can help with initial drafts. Proofed can then check the result offline. That combination keeps everything on-device from draft to final check.
Proofed is available on the App Store. Runs on iOS 17+. No account. No internet required. Your documents stay on your phone.