diff --git a/app/controllers/api/v1/sessions_controller.rb b/app/controllers/api/v1/sessions_controller.rb
index 4eecb75..404e14c 100644
--- a/app/controllers/api/v1/sessions_controller.rb
+++ b/app/controllers/api/v1/sessions_controller.rb
@@ -3,30 +3,28 @@ class Api::V1::SessionsController < ApplicationController
   before_action :authorize, only: [:destroy]
 
   def create
-    if params[:email].present? && params[:password].present?
-      returning_user = User.find_by(email: params[:email])
-
-      # the & is called a "safe navigation" operator
-      # It prevent a "NoMethodError" from being raised when invoking a method on nil
-      if returning_user&.authenticate(params[:password])
-        session[:user_id] = returning_user.id
-        render json: UserSerializer.new(returning_user), status: :created
-      else
-        render json: { error: 'Invalid email or password' }, status: :unauthorized
-      end
-    else
-      render json: { error: 'Email and password are required' }, status: :unprocessable_entity
-    end
+    authenticate_user
+    session[:user_id] = @returning_user.id
+    render json: UserSerializer.new(@returning_user), status: :created
   end
 
   def destroy
     session.delete(:user_id)
-    head :no_content
+    head :no_content # Ensures that the client receives an HTTP status code of 204 No Content along with an empty response body
   end
 
   private
   
   def authorize
-    render json: { error: 'Not authorized' }, status: :unauthorized unless session[:user_id]
+    raise UnauthorizedException if params[:user_id].to_i != session[:user_id]
+  end
+
+  def authenticate_user
+    if params[:email].present? && params[:password].present?
+      @returning_user = User.find_by(email: params[:email])
+      raise InvalidAuthenticationException unless @returning_user&.authenticate(params[:password]) # The & is a 'safe navigation operator' which allows you to call a method on an object only if that object is not nil 
+    else 
+      raise MissingAuthenticationException
+    end
   end
-end
+end
\ No newline at end of file
diff --git a/app/controllers/application_controller.rb b/app/controllers/application_controller.rb
index 890c760..07d1a43 100644
--- a/app/controllers/application_controller.rb
+++ b/app/controllers/application_controller.rb
@@ -6,6 +6,14 @@ class ApplicationController < ActionController::API
   rescue_from NoPuzzlesFoundException, with: :no_puzzles_found
   rescue_from PuzzleNotAvailableException, with: :puzzle_not_available
   rescue_from NoLoanUpdateException, with: :no_loan_update
+  rescue_from InvalidAuthenticationException, with: :invalid_authentication
+  rescue_from MissingAuthenticationException, with: :missing_authentication
+  rescue_from UnauthorizedException, with: :unauthorized
+
+
+  def set_current_user
+    @current_user ||= User.find_by(id: session[:user_id])
+  end
 
   def record_not_found(exception)
     render json: ErrorSerializer.new(exception, 404).serializable_hash, status: :not_found # 404
@@ -26,9 +34,21 @@ def no_loan_update
     render json: ErrorSerializer.new(error, 404).serializable_hash, status: :not_found # 404
   end
 
-  def set_current_user
-    @current_user ||= User.find_by(id: session[:user_id])
+  def invalid_authentication
+    error = InvalidAuthenticationException.new("Invalid email or password.")
+    render json: ErrorSerializer.new(error, 401).serializable_hash, status: :unauthorized # 401
+  end
+
+  def missing_authentication
+    error = MissingAuthenticationException.new("Email and password are required.")
+    render json: ErrorSerializer.new(error, 401).serializable_hash, status: :unauthorized # 401
   end
+
+  def unauthorized
+    error = UnauthorizedException.new("Not Authorized.")
+    render json: ErrorSerializer.new(error, 401).serializable_hash, status: :unauthorized # 401
+  end
+
 end
 
 # Note to self: Saving this to remember process that lead me to final version:
diff --git a/app/exceptions/invalid_authentication_exception.rb b/app/exceptions/invalid_authentication_exception.rb
new file mode 100644
index 0000000..4c3a5a6
--- /dev/null
+++ b/app/exceptions/invalid_authentication_exception.rb
@@ -0,0 +1,2 @@
+class InvalidAuthenticationException < StandardError
+end
\ No newline at end of file
diff --git a/app/exceptions/missing_authentication_exception.rb b/app/exceptions/missing_authentication_exception.rb
new file mode 100644
index 0000000..4be74ef
--- /dev/null
+++ b/app/exceptions/missing_authentication_exception.rb
@@ -0,0 +1,2 @@
+class MissingAuthenticationException < StandardError
+end
\ No newline at end of file
diff --git a/app/exceptions/unauthorized_exception.rb b/app/exceptions/unauthorized_exception.rb
new file mode 100644
index 0000000..62b7b90
--- /dev/null
+++ b/app/exceptions/unauthorized_exception.rb
@@ -0,0 +1,2 @@
+class UnauthorizedException < StandardError
+end
\ No newline at end of file
diff --git a/spec/requests/api/v1/sessions_request_spec.rb b/spec/requests/api/v1/sessions_request_spec.rb
index 02263cb..555010e 100644
--- a/spec/requests/api/v1/sessions_request_spec.rb
+++ b/spec/requests/api/v1/sessions_request_spec.rb
@@ -2,17 +2,19 @@
 
 RSpec.describe 'SessionsController' do
   describe '#create' do
+    before(:each) do
+      @user = User.create(
+        full_name: "Diana Puzzler",
+        password: "PuzzleQueen1",
+        password_confirmation: "PuzzleQueen1",
+        email: "dpuzzler@myemail.com", # The Users#create will format the email in this way before it is saved to the db
+        zip_code: 12345,
+        phone_number: "(555) 000-9999" # The Users#create will format the phone_number in this way before it is saved to the db
+      )
+    end
+
     context 'when successful' do
       it 'logs in a user' do
-        user = User.create(
-          full_name: "Diana Puzzler",
-          password: "PuzzleQueen1",
-          password_confirmation: "PuzzleQueen1",
-          email: "dpuzzler@myemail.com",
-          zip_code: 12345,
-          phone_number: 5500009999
-        )
-
         login_data = {
           email: "dpuzzler@myemail.com",
           password: "PuzzleQueen1"
@@ -22,21 +24,14 @@
         post "/api/v1/login", headers:, params: JSON.generate(login_data)
 
         expect(response).to have_http_status(201)
-        expect(session[:user_id]).to eq(user.id)
+        parsed_data = JSON.parse(response.body, symbolize_names: true)
+
+        expect(session[:user_id]).to eq(@user.id)
       end
     end
 
     context 'when NOT successful' do
       it 'cannot log in a user with an incorrect password' do
-        user = User.create(
-          full_name: "Diana Puzzler",
-          password: "PuzzleQueen1",
-          password_confirmation: "PuzzleQueen1",
-          email: "dpuzzler@myemail.com",
-          zip_code: 12345,
-          phone_number: 5550009999
-        )
-
         login_data = {
           email: "dpuzzler@myemail.com",
           password: "Queen_of_Puzzles"
@@ -46,12 +41,38 @@
         post "/api/v1/login", headers:, params: JSON.generate(login_data)
 
         expect(response).to have_http_status(401)
+        parsed_error_data = JSON.parse(response.body, symbolize_names: true)
+
+        expect(parsed_error_data).to be_a(Hash)
+        expect(parsed_error_data.keys).to eq([:errors])
+        expect(parsed_error_data[:errors]).to be_an(Array)
+        expect(parsed_error_data[:errors][0]).to be_a(Hash)
+        expect(parsed_error_data[:errors][0].keys).to eq([:status, :title, :detail])
+        expect(parsed_error_data[:errors][0][:status]).to eq("401")
+        expect(parsed_error_data[:errors][0][:title]).to eq("InvalidAuthenticationException")
+        expect(parsed_error_data[:errors][0][:detail]).to eq("Invalid email or password.")
+      end
 
+      it 'cannot log in a user with a missing email and password' do
+        login_data = {
+          email: nil,
+          password: nil
+        }
+
+        headers = { 'CONTENT_TYPE' => 'application/json' }
+        post "/api/v1/login", headers:, params: JSON.generate(login_data)
+
+        expect(response).to have_http_status(401)
         parsed_error_data = JSON.parse(response.body, symbolize_names: true)
 
         expect(parsed_error_data).to be_a(Hash)
-        expect(parsed_error_data.keys).to eq([:error])
-        expect(parsed_error_data[:error]).to eq("Invalid email or password")
+        expect(parsed_error_data.keys).to eq([:errors])
+        expect(parsed_error_data[:errors]).to be_an(Array)
+        expect(parsed_error_data[:errors][0]).to be_a(Hash)
+        expect(parsed_error_data[:errors][0].keys).to eq([:status, :title, :detail])
+        expect(parsed_error_data[:errors][0][:status]).to eq("401")
+        expect(parsed_error_data[:errors][0][:title]).to eq("MissingAuthenticationException")
+        expect(parsed_error_data[:errors][0][:detail]).to eq("Email and password are required.")
       end
     end
   end
@@ -76,23 +97,23 @@
     end
 
     context 'when NOT successful' do
-      # Unsure how to test this:
+      it 'cannot delete a user session of another user' do
+        user_1 = create(:user)
+        user_2 = create(:user)
+        login_data = { email: user_1.email, password: user_1.password }
 
-      # it 'cannot delete a user session of another user' do
-      #   user = create(:user)
-      #   login_data = { email: user.email, password: user.password }
-
-      #   headers = { 'CONTENT_TYPE' => 'application/json' }
-      #   post "/api/v1/users/#{user.id}/login", headers:, params: JSON.generate(login_data)
+        headers = { 'CONTENT_TYPE' => 'application/json' }
+        post "/api/v1/login", headers:, params: JSON.generate(login_data)
 
-      #   expect(response).to have_http_status(201)
-      #   expect(session[:user_id]).to eq(user.id)
+        expect(response).to have_http_status(201)
+        expect(session[:user_id]).to eq(user_1.id)
+        session_token_user1 = JSON.parse(response.body)['session_token']
 
-      #   delete "/api/v1/users/007/logout"
+        delete "/api/v1/users/#{user_2.id}/logout", headers: { 'Authorization' => "Bearer #{session_token_user1}" }
 
-      #   expect(response).to have_http_status(401)
-      #   expect(session[:user_id]).to eq(user.id)
-      # end
+        expect(response).to have_http_status(401)
+        expect(session[:user_id]).to eq(user_1.id)
+      end
     end
   end
 end