diff --git a/lib/stytch/b2b_client.rb b/lib/stytch/b2b_client.rb
index 9cbdb42..c081236 100644
--- a/lib/stytch/b2b_client.rb
+++ b/lib/stytch/b2b_client.rb
@@ -6,15 +6,17 @@
 require_relative 'b2b_organizations'
 require_relative 'b2b_otp'
 require_relative 'b2b_passwords'
+require_relative 'b2b_rbac'
 require_relative 'b2b_sessions'
 require_relative 'b2b_sso'
 require_relative 'm2m'
+require_relative 'rbac_local'
 
 module StytchB2B
   class Client
     ENVIRONMENTS = %i[live test].freeze
 
-    attr_reader :discovery, :m2m, :magic_links, :oauth, :otps, :organizations, :passwords, :sso, :sessions
+    attr_reader :discovery, :m2m, :magic_links, :oauth, :otps, :organizations, :passwords, :rbac, :sso, :sessions
 
     def initialize(project_id:, secret:, env: nil, &block)
       @api_host   = api_host(env, project_id)
@@ -23,15 +25,19 @@ def initialize(project_id:, secret:, env: nil, &block)
 
       create_connection(&block)
 
+      rbac = StytchB2B::RBAC.new(@connection)
+      @policy_cache = StytchB2B::PolicyCache.new(rbac_client: rbac)
+
       @discovery = StytchB2B::Discovery.new(@connection)
-      @m2m = Stytch::M2M.new(@connection, project_id)
+      @m2m = Stytch::M2M.new(@connection, @project_id)
       @magic_links = StytchB2B::MagicLinks.new(@connection)
       @oauth = StytchB2B::OAuth.new(@connection)
       @otps = StytchB2B::OTPs.new(@connection)
       @organizations = StytchB2B::Organizations.new(@connection)
       @passwords = StytchB2B::Passwords.new(@connection)
+      @rbac = StytchB2B::RBAC.new(@connection)
       @sso = StytchB2B::SSO.new(@connection)
-      @sessions = StytchB2B::Sessions.new(@connection, project_id)
+      @sessions = StytchB2B::Sessions.new(@connection, @project_id, @policy_cache)
     end
 
     private
diff --git a/lib/stytch/b2b_rbac.rb b/lib/stytch/b2b_rbac.rb
new file mode 100644
index 0000000..5b7f7f2
--- /dev/null
+++ b/lib/stytch/b2b_rbac.rb
@@ -0,0 +1,25 @@
+# frozen_string_literal: true
+
+# !!!
+# WARNING: This file is autogenerated
+# Only modify code within MANUAL() sections
+# or your changes may be overwritten later!
+# !!!
+
+require_relative 'request_helper'
+
+module StytchB2B
+  class RBAC
+    include Stytch::RequestHelper
+
+    def initialize(connection)
+      @connection = connection
+    end
+
+    def policy
+      query_params = {}
+      request = request_with_query_params('/v1/b2b/rbac/policy', query_params)
+      get_request(request)
+    end
+  end
+end
diff --git a/lib/stytch/b2b_sessions.rb b/lib/stytch/b2b_sessions.rb
index 4b913f4..166d464 100644
--- a/lib/stytch/b2b_sessions.rb
+++ b/lib/stytch/b2b_sessions.rb
@@ -15,9 +15,10 @@ module StytchB2B
   class Sessions
     include Stytch::RequestHelper
 
-    def initialize(connection, project_id)
+    def initialize(connection, project_id, policy_cache)
       @connection = connection
 
+      @policy_cache = policy_cache
       @project_id = project_id
       @cache_last_update = 0
       @jwks_loader = lambda do |options|
@@ -95,6 +96,9 @@ def get(
     #   delete a key, supply a null value. Custom claims made with reserved claims (`iss`, `sub`, `aud`, `exp`, `nbf`, `iat`, `jti`) will be ignored.
     #   Total custom claims size cannot exceed four kilobytes.
     #   The type of this field is nilable +object+.
+    # authorization_check::
+    #   (no documentation yet)
+    #   The type of this field is nilable +AuthorizationCheck+ (+object+).
     #
     # == Returns:
     # An object with the following fields:
@@ -123,13 +127,15 @@ def authenticate(
       session_token: nil,
       session_duration_minutes: nil,
       session_jwt: nil,
-      session_custom_claims: nil
+      session_custom_claims: nil,
+      authorization_check: nil
     )
       request = {}
       request[:session_token] = session_token unless session_token.nil?
       request[:session_duration_minutes] = session_duration_minutes unless session_duration_minutes.nil?
       request[:session_jwt] = session_jwt unless session_jwt.nil?
       request[:session_custom_claims] = session_custom_claims unless session_custom_claims.nil?
+      request[:authorization_check] = authorization_check unless authorization_check.nil?
 
       post_request('/v1/b2b/sessions/authenticate', request)
     end
@@ -325,17 +331,21 @@ def get_jwks(
     # If max_token_age_seconds is set and the JWT was issued (based on the "iat" claim) less than
     # max_token_age_seconds seconds ago, then just verify locally and don't call the API
     # To force remote validation for all tokens, set max_token_age_seconds to 0 or call authenticate()
+    # Note that the 'user_id' field of the returned session is DEPRECATED: Use member_id instead
+    # This field will be removed in a future MAJOR release.
     def authenticate_jwt(
       session_jwt,
       max_token_age_seconds: nil,
       session_duration_minutes: nil,
-      session_custom_claims: nil
+      session_custom_claims: nil,
+      authorization_check: nil
     )
       if max_token_age_seconds == 0
         return authenticate(
           session_jwt: session_jwt,
           session_duration_minutes: session_duration_minutes,
-          session_custom_claims: session_custom_claims
+          session_custom_claims: session_custom_claims,
+          authorization_check: authorization_check
         )
       end
 
@@ -343,12 +353,21 @@ def authenticate_jwt(
       iat_time = Time.at(decoded_jwt['iat']).to_datetime
       if iat_time + max_token_age_seconds >= Time.now
         session = marshal_jwt_into_session(decoded_jwt)
-        { 'session' => session }
+        if authorization_check && session['roles']
+          @policy_cache.perform_authorization_check(
+            subject_roles: session['roles'],
+            subject_org_id: session['organization_id'],
+            authorization_check: authorization_check
+          )
+        end
+
+        { 'session' => session['member_session'] }
       else
         authenticate(
           session_jwt: session_jwt,
           session_duration_minutes: session_duration_minutes,
-          session_custom_claims: session_custom_claims
+          session_custom_claims: session_custom_claims,
+          authorization_check: authorization_check
         )
       end
     rescue StandardError
@@ -356,7 +375,8 @@ def authenticate_jwt(
       authenticate(
         session_jwt: session_jwt,
         session_duration_minutes: session_duration_minutes,
-        session_custom_claims: session_custom_claims
+        session_custom_claims: session_custom_claims,
+        authorization_check: authorization_check
       )
     end
 
@@ -381,24 +401,35 @@ def authenticate_jwt_local(session_jwt)
       end
     end
 
+    # Note that the 'user_id' field is DEPRECATED: Use member_id instead
+    # This field will be removed in a future MAJOR release.
     def marshal_jwt_into_session(jwt)
       stytch_claim = 'https://stytch.com/session'
+      organization_claim = 'https://stytch.com/organization'
+      roles_claim = 'https://stytch.com/roles'
+
       expires_at = jwt[stytch_claim]['expires_at'] || Time.at(jwt['exp']).to_datetime.utc.strftime('%Y-%m-%dT%H:%M:%SZ')
       # The custom claim set is all the claims in the payload except for the standard claims and
       # the Stytch session claim. The cleanest way to collect those seems to be naming what we want
       # to omit and filtering the rest to collect the custom claims.
-      reserved_claims = ['aud', 'exp', 'iat', 'iss', 'jti', 'nbf', 'sub', stytch_claim]
+      reserved_claims = ['aud', 'exp', 'iat', 'iss', 'jti', 'nbf', 'sub', stytch_claim, organization_claim, roles_claim]
       custom_claims = jwt.reject { |key, _| reserved_claims.include?(key) }
       {
-        'session_id' => jwt[stytch_claim]['id'],
-        'user_id' => jwt['sub'],
-        'started_at' => jwt[stytch_claim]['started_at'],
-        'last_accessed_at' => jwt[stytch_claim]['last_accessed_at'],
-        # For JWTs that include it, prefer the inner expires_at claim.
-        'expires_at' => expires_at,
-        'attributes' => jwt[stytch_claim]['attributes'],
-        'authentication_factors' => jwt[stytch_claim]['authentication_factors'],
-        'custom_claims' => custom_claims
+        'member_session' => {
+          'session_id' => jwt[stytch_claim]['id'],
+          'organization_id' => jwt[organization_claim]['id'],
+          'member_id' => jwt['sub'],
+          # DEPRECATED: Use member_id instead
+          'user_id' => jwt['sub'],
+          'started_at' => jwt[stytch_claim]['started_at'],
+          'last_accessed_at' => jwt[stytch_claim]['last_accessed_at'],
+          # For JWTs that include it, prefer the inner expires_at claim.
+          'expires_at' => expires_at,
+          'attributes' => jwt[stytch_claim]['attributes'],
+          'authentication_factors' => jwt[stytch_claim]['authentication_factors'],
+          'custom_claims' => custom_claims
+        },
+        'roles' => jwt[roles_claim]
       }
     end
     # ENDMANUAL(Sessions::authenticate_jwt)
diff --git a/lib/stytch/client.rb b/lib/stytch/client.rb
index d7b315d..9b42f8b 100644
--- a/lib/stytch/client.rb
+++ b/lib/stytch/client.rb
@@ -25,12 +25,12 @@ def initialize(project_id:, secret:, env: nil, &block)
       create_connection(&block)
 
       @crypto_wallets = Stytch::CryptoWallets.new(@connection)
-      @m2m = Stytch::M2M.new(@connection, project_id)
+      @m2m = Stytch::M2M.new(@connection, @project_id)
       @magic_links = Stytch::MagicLinks.new(@connection)
       @oauth = Stytch::OAuth.new(@connection)
       @otps = Stytch::OTPs.new(@connection)
       @passwords = Stytch::Passwords.new(@connection)
-      @sessions = Stytch::Sessions.new(@connection, project_id)
+      @sessions = Stytch::Sessions.new(@connection, @project_id)
       @totps = Stytch::TOTPs.new(@connection)
       @users = Stytch::Users.new(@connection)
       @webauthn = Stytch::WebAuthn.new(@connection)
diff --git a/lib/stytch/errors.rb b/lib/stytch/errors.rb
index acab36e..1ffdc02 100644
--- a/lib/stytch/errors.rb
+++ b/lib/stytch/errors.rb
@@ -35,4 +35,18 @@ def initialize(scope)
       super(msg)
     end
   end
+
+  class TenancyError < StandardError
+    def initialize(subject_org_id, request_org_id)
+      msg = "Subject organization_id #{subject_org_id} does not match authZ request organization_id #{request_org_id}"
+      super(msg)
+    end
+  end
+
+  class PermissionError < StandardError
+    def initialize(request)
+      msg = "Permission denied for request #{request}"
+      super(msg)
+    end
+  end
 end
diff --git a/lib/stytch/rbac_local.rb b/lib/stytch/rbac_local.rb
new file mode 100644
index 0000000..63916f3
--- /dev/null
+++ b/lib/stytch/rbac_local.rb
@@ -0,0 +1,56 @@
+# frozen_string_literal: true
+
+require_relative 'request_helper'
+
+module StytchB2B
+  class PolicyCache
+    def initialize(rbac_client:)
+      @rbac_client = rbac_client
+      @policy_last_update = 0
+      @cached_policy = nil
+    end
+
+    def reload_policy
+      @cached_policy = rbac_client.get_policy
+      @policy_last_update = Time.now.to_i
+    end
+
+    def get_policy(invalidate: false)
+      reload_policy if invalidate || @cached_policy.nil? || @policy_last_update < Time.now.to_i - 300
+      @cached_policy
+    end
+
+    # Performs an authorization check against the project's policy and a set of roles. If the
+    # check succeeds, this method will return. If the check fails, a PermissionError
+    # will be raised. It's also possible for a TenancyError to be raised if the
+    # subject_org_id does not match the authZ request organization_id.
+    # authorization_check is an object with keys 'action', 'resource_id', and 'organization_id'
+    def perform_authorization_check(
+      subject_roles:,
+      subject_org_id:,
+      authorization_check:
+    )
+      raise TenancyError, subject_org_id if subject_org_id != authorization_check['organization_id']
+
+      policy = get_policy
+
+      for role in policy['roles']
+        next unless subject_roles.include?(role['role_id'])
+
+        for permission in role['permissions']
+          actions = permission['actions']
+          resource = permission['resource_id']
+          has_matching_action = actions.include?('*') || actions.include?(authorization_check['action'])
+          has_matching_resource = resource == authorization_check['resource_id']
+          if has_matching_action && has_matching_resource
+            # All good
+            return
+          end
+        end
+      end
+
+      # If we get here, we didn't find a matching permission
+      raise PermissionError, authorization_check
+    end
+  end
+end