> ## Documentation Index
> Fetch the complete documentation index at: https://docs.platform.arb.inc/llms.txt
> Use this file to discover all available pages before exploring further.

# Add participant to case

> Adds a participant from your organization to an existing case. The participant will have the same party role as the requester.



## OpenAPI

````yaml api-reference/cases.yaml post /participants/add
openapi: 3.0.3
info:
  title: cases
  description: >-
    The Cases Service is the main place where all case info lives, including who
    is involved and what files are attached. It lets you create new cases, view
    existing ones, upload documents or files, and manage service of notice
    delivery through multiple channels (mail, email, or manual attestation),
    while notifying other parts of the system when anything changes.
  version: 1.0.0
servers:
  - url: https://cases.platform.arb.inc
security: []
tags:
  - name: /
  - name: cases
  - name: docket
  - name: evidence
  - name: filings
  - name: internal
  - name: invites
  - name: participants
  - name: schemas
  - name: service-of-notice
  - name: tasks
  - name: timetables
paths:
  /participants/add:
    post:
      tags:
        - participants
      summary: Add participant to case
      description: >-
        Adds a participant from your organization to an existing case. The
        participant will have the same party role as the requester.
      operationId: addParticipant
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              required:
                - caseID
                - userID
              properties:
                caseID:
                  type: string
                  description: Target case identifier
                  example: 2025-08-00292
                userID:
                  type: string
                  format: uuid
                  description: UUID of the user being added
                  example: 2720f109-0caf-4c62-af22-5d08c853711c
                isObserver:
                  type: boolean
                  description: Whether the user is added as an observer
                  example: false
      responses:
        '200':
          description: Successfully added participant
          content:
            text/plain:
              schema:
                type: string
                example: participant was successfully added to the case
      security:
        - bearerAuth: []
components:
  securitySchemes:
    bearerAuth:
      type: http
      description: access token
      scheme: bearer
      bearerFormat: JWT

````