What an Ethical Wall Is and When a Firm Needs One

An ethical wall, also called a screen, is a set of procedures that isolates a lawyer or staff member from a specific matter so that confidential information does not flow to or from that person. It combines written notice to everyone involved, a prohibition on discussing the matter, and technical restrictions that prevent the screened person from opening the files.

Firms build walls for a few recurring reasons. A lateral hire arrives with knowledge of a former client that is now adverse to one of the firm's clients. A paralegal or secretary previously worked at opposing counsel's office. Two clients of the same firm end up on opposite sides of a transaction with informed consent on both sides, conditioned on separation. In each case the wall exists because someone inside the firm has a duty of confidentiality to a party that conflicts with the firm's work, and the wall is how the firm keeps both promises at once.

The Conflict Rules Behind the Wall

Whether a screen is permitted at all is a question of professional responsibility, not technology, and the answer differs by jurisdiction. ABA Model Rule 1.10(a)(2) allows a firm to avoid imputation of a lateral lawyer's former-client conflict if the lawyer is timely screened and apportioned no part of the fee, the affected former client receives prompt written notice describing the screening procedures, and the firm provides certifications of compliance when asked. California's Rule 1.10(a)(2) is narrower: screening is available only if the prohibited lawyer did not substantially participate in the same or a substantially related matter, and the same notice and fee-apportionment conditions apply.

The practical lesson for a firm's technology is that a wall has to be decided by counsel first and built by IT second, and it has to be built quickly. "Timely screened" means the restrictions are in place before the conflicted person could have seen anything, which in a modern firm means before their account is created, not after someone remembers a week later. A screen that was set up late is a screen the former client's lawyers will attack, and the audit log will show exactly when it went up.

Walls Are the Exception, Need-to-Know Is the Rule

A formal wall handles the rare conflict. Matter-level access control is the everyday version: each matter is visible only to the people working on it, and everyone else in the firm is excluded by default rather than by special arrangement. It is not required by the conflict rules, since a firm's lawyers generally may share information within the firm for purposes of the representation, but it is what ABA Formal Opinion 477R's "reasonable efforts" standard increasingly looks like in practice, and it is what clients now ask about directly.

Need-to-know also changes what a breach costs. When one attorney's mailbox is compromised, the attacker inherits that attorney's permissions, and in a default-open firm that means every matter the firm has ever handled. In a need-to-know firm the same incident exposes a dozen matters instead of a thousand, and the firm can tell each affected client precisely what was reachable, which is a very different notification letter to write. That containment is the practical payoff of treating access control as a design decision rather than a setting someone once chose.

Why "Everyone Can See Everything" Is the Default in Most Small Firms

The open default is not negligence, it is history. Shared drives were organized by client name and everyone had the drive letter. Early document management deployments made the whole library visible because that was the easiest way to get people to use it. Microsoft 365 arrived and the firm made one SharePoint site called "Clients" with every employee as a member, because that is what the setup wizard suggested and it worked. Each decision was reasonable, and the cumulative result is a firm where a summer clerk can search for a partner's most sensitive negotiation and open the term sheet.

Three developments have turned that inconvenience into a risk. Corporate clients' outside counsel guidelines now ask who inside the firm can access their information and expect an answer more specific than "our employees." Lateral movement in the legal market means conflicts arrive more often and with less warning. And generative AI assistants built into office software surface whatever the signed-in user is permitted to see, which means an over-permissioned tenant that used to leak only when someone went looking now answers questions about other people's matters on request.

The good news is that the same permission model that makes AI assistants safe makes everything else safe. Those tools respect existing access controls, so a firm that fixes matter-level permissions once fixes search, sharing, and AI exposure together rather than chasing each separately.

How Matter-Level Access Control Actually Works

The model is simple to state and demanding to maintain. The matter, not the client and not the practice group, is the unit of access. Every matter has a defined team, membership in that team is what grants access, and a person who leaves the team loses access on the day they leave it. Everything below is a way of making a system enforce that sentence.

The Matter as the Unit of Access

Firms that try to control access at the client level discover quickly that the client is too coarse. A firm may handle a client's routine employment work with one team and a sensitive internal investigation with another, and the investigation team has no business seeing the employment files or vice versa. Treating each matter as its own container, with its own membership, is what lets the same client have matters at different sensitivity levels without inventing special cases.

Most firms end up with three tiers. Open matters are visible to the practice group or the whole firm because there is no reason to restrict them, such as general corporate housekeeping. Restricted matters are visible to the matter team only, which should be the default for anything involving litigation strategy, transactions before announcement, personal or health information, or a client whose guidelines require it. Walled matters are restricted matters with named exclusions, the technical expression of an ethical wall.

Who Belongs on a Matter Team

The responsible attorney, the associates and paralegals staffed on the matter, and the assistants who support them belong on the team. Accounting and billing staff usually need matter metadata, such as the client name, matter number, and time entries, but not the documents, and a well-designed system gives them the first without the second. Conflicts and records staff need to know that a matter exists and who is on it, which is again metadata rather than content.

The people who most often end up with silent access are the ones with administrative roles: the office manager who was made a site owner to fix something once, the former associate whose account was never removed, and the IT staff or provider whose administrative rights reach everything by design. The first two are access review problems. The third is a privileged access management problem, and it deserves its own controls, covered below.

Implementing Matter-Level Access in a Document Management System

Legal document management systems such as iManage and NetDocuments were built for this model, which is the strongest argument for using one rather than a general-purpose file share. Each matter is a workspace with its own security setting, membership is managed by group, search results only show documents the user can open, and every open, edit, download, and share is logged against a named user. Both platforms also offer dedicated ethical wall functionality that lets a firm exclude specific people from specific matters while keeping the rest of the membership intact, and that produces the wall report counsel needs for the screening certification.

The weakness is not the software, it is the default. Many DMS deployments were installed with every workspace set to public because the firm was migrating from an open file share and did not want to break anyone's access on cutover day. Changing the default to restricted for new matters, and then working through existing matters by sensitivity, is the project most firms need and few have done. The same attention to where a document can travel applies to the secure file sharing for law firms that the DMS feeds, because a restricted workspace is undone by an unrestricted link.

Implementing Matter-Level Access in Microsoft 365 and SharePoint

A firm without a legal DMS can still run a need-to-know model in Microsoft 365, with more discipline and fewer conveniences. The workable pattern is one SharePoint site per client, one document library or folder set per matter, and one security group per matter team that owns the permissions on that library. Permissions are assigned to the group, never to individuals, so adding a paralegal to a matter means adding her to one group and removing her means removing her from one group, with the change reflected everywhere the group is used.

Sensitivity labels add a second layer that travels with the file. A label applied to a matter library can encrypt the documents so that even a copy emailed outside the team cannot be opened by someone who is not a member, and the same labels drive data loss prevention rules that warn or block when a restricted document leaves the firm. Teams private channels and shared channels map naturally onto matter teams for chat and meetings, and OneDrive sharing defaults should be set so that "anyone with the link" is not an option for matter content. Getting this right is a configuration project, and it is one of the most common reasons firms bring in outside Microsoft 365 support rather than attempting it between client deadlines.

One honest limitation: Microsoft's Information Barriers feature, which enforces communication and collaboration restrictions between defined groups of people across Teams, SharePoint, and OneDrive, requires Microsoft 365 E5 or a Purview add-on and is not part of Business Premium. A small firm can build a solid wall with groups, labels, and distribution list hygiene, but it should not expect the tenant to enforce "these two people may never message each other" without that licensing.

The Permission Sprawl Problem

SharePoint permissions degrade quietly. Someone breaks inheritance on a folder to share one document, a nested group gets added to another group, a link is created for "people in your organization" and forgotten, and two years later nobody can say from memory who can reach a given library. Microsoft's own admin tools and a growing set of third-party reports can show the effective permissions on any site, and a firm should run that report before it makes any promise to a client about internal access.

The fix is structural rather than heroic. Keep inheritance intact below the matter level, prohibit direct user permissions, require that every sharing link have an expiration, and review effective access on the firm's most sensitive matters on a fixed schedule. The principles are the same ones that make role-based access control work in any business; the legal twist is that the role is defined by the matter rather than the job title.

Email and Chat Are Part of the Matter Too

A wall that covers the document library and ignores email is not a wall. A screened lawyer who is still on the matter's distribution list, still in its Teams channel, or still copied on the calendar invitations has been told everything the documents would have told them. Matter teams should therefore drive email distribution groups and chat membership as well as file permissions, and a screening memo should list every channel the screened person has been removed from, not just the DMS workspace.

Conversation data also deserves the same classification thinking as documents, because a restricted matter's strategy is as likely to live in a chat thread as in a memo. The firm's data classification scheme should say which matter tiers require which handling in email and chat, and the technical controls should follow the scheme rather than the other way around.

Privileged Accounts and the People Who Can See Everything

Administrators, whether in-house or at the firm's IT provider, can technically reach every matter, and no permission model changes that. What a firm can do is narrow the set of people with that power and require separate administrative accounts, used only for administration and protected with phishing-resistant multi-factor authentication. It can grant administrative rights for a limited time when a task requires them, and it can log every use so that an administrator opening a restricted matter is visible and explainable. A client asking about internal access will accept "three named administrators, just-in-time administrative rights, full logging" far more readily than "our IT company has the password."

This is also where the firm's choice of provider matters. An outside provider that runs its own engineers through the same privileged access controls it recommends to clients, with background checks, named accounts, and logged sessions, can be included in the firm's answer to a client without embarrassment. One that shares a single administrator login among its staff cannot.

Building an Ethical Wall Step by Step When a Conflict Arises

When the conflicts check flags a lateral or a matter, the wall has to go from decision to enforcement in hours. The sequence that satisfies both counsel and an auditor looks like this:

1. Conflicts staff identify the conflicted person and the affected matters, and counsel decides whether screening is permitted under the applicable rule and whether former-client notice is required.
2. Counsel issues a written screening memorandum naming the screened person, the matters, the prohibited conduct, and the people responsible for maintaining the wall.
3. IT removes the screened person from the matter workspaces, security groups, distribution lists, chat channels, and shared calendars, and applies the DMS ethical wall or label restriction so that search and direct links fail for that person.
4. Records staff secure any physical files and label them with the screening restriction.
5. The screened person and the matter team each sign an acknowledgment of the memorandum.
6. The firm sends any required written notice to the affected former client describing the procedures.
7. IT enables alerting on any attempted access by the screened person to the walled matters, and the firm reviews the wall at set intervals and at the end of the matter.
8. Every step is dated and filed with the conflicts record, because the screening certification depends on being able to show when each control took effect.

The Lateral Hire Timing Problem

The hardest wall to get right is the one for a lawyer who has not started yet. The conflicts review happens during recruiting, the restrictions must be in place before the account is provisioned, and the onboarding checklist has to carry the screening instruction to the person who creates the accounts. Firms that treat account creation as a purely administrative step, handled the morning the lateral arrives, routinely discover that the new lawyer had firm-wide access for several days before anyone applied the wall.

The answer is to make conflicts clearance an input to the technical onboarding rather than a separate track. The checklist in our guide to IT onboarding and offboarding is a reasonable starting point; a law firm's version adds a mandatory field for screening restrictions that must be completed before provisioning can proceed.

Access Reviews: Keeping Matter Teams Accurate Over Time

Matter-level access is only as accurate as the last time someone checked it. People move between matters, associates leave, matters close, and the permission that was correct in March is wrong by September. A quarterly review of the firm's restricted and walled matters, in which the responsible attorney confirms the current team and IT reconciles the groups against that list, catches most drift, and a matter-close procedure that removes everyone except the records custodian catches the rest.

The review also interacts with preservation. A matter under legal hold may need to keep its access restrictions while preservation controls stop deletion, and the two settings are managed in different places, which is a detail worth writing into the procedure so the legal hold in Microsoft 365 and the matter permissions are changed by people who know about each other.

What Clients Now Ask, and What a Good Answer Sounds Like

Corporate legal departments have started asking law firms a short, specific set of questions: which of your people can open our matters, how is that enforced technically, how would you know if someone outside the team opened a file, and can you show us a log. A firm running matter-level access can answer all four in a paragraph and attach a report. A firm running firm-wide access can answer the first question honestly and then has a difficult conversation about the other three.

For firms in the San Fernando Valley and across Los Angeles, where a single mid-sized practice may serve entertainment, healthcare, real estate, and financial clients with very different expectations, the matter-level model is also what lets one firm satisfy all of them without running four separate security programs. GlobeVM's work with law firms on this problem usually begins with an effective-permissions report, because the first step is knowing what the current answer actually is.

The same report tends to settle internal debates. Partners who resist restricting access on the grounds that "we are all one firm" often change their view when they see how many former employees, vendors, and summer clerks still appear on it, and the project becomes one of cleaning up rather than locking down. The conversation shifts from whether to restrict access to how quickly the cleanup can be done.

Make Need-to-Know the Default and Walls the Exception

Ethical walls get the attention because conflicts are dramatic, but the firm that only builds walls is still open by default everywhere else. The durable fix is to make the matter the unit of access, assign permissions through matter teams, keep email and chat inside the model, control the administrators who can bypass it, and review the whole thing on a schedule.

Done that way, a wall becomes a special case of a system the firm already runs rather than an emergency project, and the client's question about who can open its files gets an answer the firm is glad to give; our overview of cybersecurity for law firms shows where that system sits among the other controls a practice needs. If your firm cannot currently produce a list of who can access its most sensitive matter, an effective-permissions review is the right first step, and GlobeVM can run one with you.