Elixir & Phoenix for Legal Tech

Process Isolation for Ethical Compliance

Law firms enforce strict information barriers. Attorneys on one side of a merger cannot access documents from the other side. These ethical walls must be absolute - not best-effort, not permission-checked at the UI layer, but architecturally enforced so a software bug cannot leak privileged information.

BEAM processes provide this isolation at the runtime level. Each matter’s data access runs in its own process tree with explicit boundaries. A process handling a corporate M&A matter cannot read memory from a process handling the opposing litigation. Ecto queries scope database access through matter-specific contexts enforcing access control at the query level. Pattern matching on user roles and matter assignments rejects unauthorized access before a query executes. When ethical wall configurations change mid-matter, the supervision tree terminates affected process trees and restarts them with updated policies. Cached data purges automatically because process termination clears process state.

Deadline Management That Never Sleeps

Legal deadlines are immovable. A missed filing deadline can result in case dismissal, malpractice claims, and bar complaints. The system that tracks these deadlines must be more reliable than any individual person responsible for remembering them.

GenServer processes manage deadline state machines for each active matter. A filing deadline starts as “upcoming,” transitions through “approaching” and “urgent” as dates near, and resolves as “completed” or escalates to “overdue.” Each transition triggers notifications through Phoenix PubSub - first to the responsible attorney, then to the supervising partner. The BEAM’s scheduler guarantees these timer-based transitions fire reliably. If the GenServer crashes, the OTP supervisor restarts it, reconstructs state from Ecto, and deadline tracking continues without gaps. LiveView dashboards display deadline status in real time, updating the moment a filing is completed or a new deadline is added.

Collaborative Document Workflows

Legal documents move through drafting, review, redlining, and approval cycles involving multiple attorneys, paralegals, and sometimes external counsel. Each participant needs to see current document state and changes from others without version confusion.

LiveView makes real-time document collaboration server-authoritative. Each connected user receives DOM patches as other users make changes. Ecto tracks every document version with immutable changesets - a redline doesn’t modify the original, it creates a new version linked to its parent. Pattern matching on document state determines which actions are available: a document in “partner review” can receive comments and approvals but not structural edits from associates. Phoenix Presence shows which users are currently viewing or editing a document, preventing conflicting simultaneous edits at the UI level. Comment threads on specific clauses update in real time across all participants, enabling asynchronous review workflows that feel synchronous.

Billing Pipelines and Financial Reporting

Legal billing is complex. Time entries accumulate across multiple timekeepers on a matter. Rate structures vary by client engagement letter. Expenses require categorization and approval. Invoices must conform to client-specific billing guidelines, sometimes including LEDES format requirements.

Ecto’s composable query system handles billing aggregation cleanly. Time entries, expenses, and rate tables join through explicit, typed queries that compute matter-level and client-level totals. GenServer processes manage billing period state - tracking which entries are draft, approved, billed, or written off. The immutable data pipeline means every adjustment is traceable. Supervisors ensure that invoice generation doesn’t block the billing dashboard. Failed invoice deliveries retry automatically with exponential backoff. LiveView dashboards give billing partners real-time visibility into unbilled time, work-in-progress totals, and collection aging without manual reports.