diff --git a/docs/my-website/docs/proxy/call_hooks.md b/docs/my-website/docs/proxy/call_hooks.md
index 3195e2e5aa..3a8726e879 100644
--- a/docs/my-website/docs/proxy/call_hooks.md
+++ b/docs/my-website/docs/proxy/call_hooks.md
@@ -25,26 +25,45 @@ class MyCustomHandler(CustomLogger): # https://docs.litellm.ai/docs/observabilit
     def __init__(self):
         pass
 
-    #### ASYNC #### 
-    
-    async def async_log_stream_event(self, kwargs, response_obj, start_time, end_time):
-        pass
-
-    async def async_log_pre_api_call(self, model, messages, kwargs):
-        pass
-
-    async def async_log_success_event(self, kwargs, response_obj, start_time, end_time):
-        pass
-
-    async def async_log_failure_event(self, kwargs, response_obj, start_time, end_time):
-        pass
-
     #### CALL HOOKS - proxy only #### 
 
-    async def async_pre_call_hook(self, user_api_key_dict: UserAPIKeyAuth, cache: DualCache, data: dict, call_type: Literal["completion", "embeddings"]):
+    async def async_pre_call_hook(self, user_api_key_dict: UserAPIKeyAuth, cache: DualCache, data: dict, call_type: Literal[
+            "completion",
+            "text_completion",
+            "embeddings",
+            "image_generation",
+            "moderation",
+            "audio_transcription",
+        ]) -> Optional[dict, str, Exception]: 
         data["model"] = "my-new-model"
         return data 
 
+    async def async_post_call_failure_hook(
+        self, original_exception: Exception, user_api_key_dict: UserAPIKeyAuth
+    ):
+        pass
+
+    async def async_post_call_success_hook(
+        self,
+        user_api_key_dict: UserAPIKeyAuth,
+        response,
+    ):
+        pass
+
+    async def async_moderation_hook( # call made in parallel to llm api call
+        self,
+        data: dict,
+        user_api_key_dict: UserAPIKeyAuth,
+        call_type: Literal["completion", "embeddings", "image_generation"],
+    ):
+        pass
+
+    async def async_post_call_streaming_hook(
+        self,
+        user_api_key_dict: UserAPIKeyAuth,
+        response: str,
+    ):
+        pass
 proxy_handler_instance = MyCustomHandler()
 ```
 
@@ -190,4 +209,100 @@ general_settings:
 
 **Result**
 
-<Image img={require('../../img/end_user_enforcement.png')}/>
\ No newline at end of file
+<Image img={require('../../img/end_user_enforcement.png')}/>
+
+## Advanced - Return rejected message as response 
+
+For chat completions and text completion calls, you can return a rejected message as a user response. 
+
+Do this by returning a string. LiteLLM takes care of returning the response in the correct format depending on the endpoint and if it's streaming/non-streaming.
+
+For non-chat/text completion endpoints, this response is returned as a 400 status code exception. 
+
+
+### 1. Create Custom Handler 
+
+```python
+from litellm.integrations.custom_logger import CustomLogger
+import litellm
+from litellm.utils import get_formatted_prompt
+
+# This file includes the custom callbacks for LiteLLM Proxy
+# Once defined, these can be passed in proxy_config.yaml
+class MyCustomHandler(CustomLogger):
+    def __init__(self):
+        pass
+
+    #### CALL HOOKS - proxy only #### 
+
+    async def async_pre_call_hook(self, user_api_key_dict: UserAPIKeyAuth, cache: DualCache, data: dict, call_type: Literal[
+            "completion",
+            "text_completion",
+            "embeddings",
+            "image_generation",
+            "moderation",
+            "audio_transcription",
+        ]) -> Optional[dict, str, Exception]: 
+        formatted_prompt = get_formatted_prompt(data=data, call_type=call_type)
+
+        if "Hello world" in formatted_prompt:
+            return "This is an invalid response"
+
+        return data 
+
+proxy_handler_instance = MyCustomHandler()
+```
+
+### 2. Update config.yaml 
+
+```yaml
+model_list:
+  - model_name: gpt-3.5-turbo
+    litellm_params:
+      model: gpt-3.5-turbo
+
+litellm_settings:
+  callbacks: custom_callbacks.proxy_handler_instance # sets litellm.callbacks = [proxy_handler_instance]
+```
+
+
+### 3. Test it!
+
+```shell
+$ litellm /path/to/config.yaml
+```
+```shell
+curl --location 'http://0.0.0.0:4000/chat/completions' \
+    --data ' {
+    "model": "gpt-3.5-turbo",
+    "messages": [
+        {
+        "role": "user",
+        "content": "Hello world"
+        }
+    ],
+    }'
+```
+
+**Expected Response**
+
+```
+{
+    "id": "chatcmpl-d00bbede-2d90-4618-bf7b-11a1c23cf360",
+    "choices": [
+        {
+            "finish_reason": "stop",
+            "index": 0,
+            "message": {
+                "content": "This is an invalid response.", # 👈 REJECTED RESPONSE
+                "role": "assistant"
+            }
+        }
+    ],
+    "created": 1716234198,
+    "model": null,
+    "object": "chat.completion",
+    "system_fingerprint": null,
+    "usage": {}
+}
+```
\ No newline at end of file
diff --git a/litellm/exceptions.py b/litellm/exceptions.py
index 5eb66743b5..d189b7ebe2 100644
--- a/litellm/exceptions.py
+++ b/litellm/exceptions.py
@@ -177,6 +177,32 @@ class ContextWindowExceededError(BadRequestError):  # type: ignore
         )  # Call the base class constructor with the parameters it needs
 
 
+# sub class of bad request error - meant to help us catch guardrails-related errors on proxy.
+class RejectedRequestError(BadRequestError):  # type: ignore
+    def __init__(
+        self,
+        message,
+        model,
+        llm_provider,
+        request_data: dict,
+        litellm_debug_info: Optional[str] = None,
+    ):
+        self.status_code = 400
+        self.message = message
+        self.model = model
+        self.llm_provider = llm_provider
+        self.litellm_debug_info = litellm_debug_info
+        self.request_data = request_data
+        request = httpx.Request(method="POST", url="https://api.openai.com/v1")
+        response = httpx.Response(status_code=500, request=request)
+        super().__init__(
+            message=self.message,
+            model=self.model,  # type: ignore
+            llm_provider=self.llm_provider,  # type: ignore
+            response=response,
+        )  # Call the base class constructor with the parameters it needs
+
+
 class ContentPolicyViolationError(BadRequestError):  # type: ignore
     #  Error code: 400 - {'error': {'code': 'content_policy_violation', 'message': 'Your request was rejected as a result of our safety system. Image descriptions generated from your prompt may contain text that is not allowed by our safety system. If you believe this was done in error, your request may succeed if retried, or by adjusting your prompt.', 'param': None, 'type': 'invalid_request_error'}}
     def __init__(
diff --git a/litellm/integrations/custom_logger.py b/litellm/integrations/custom_logger.py
index d508825922..e192cdaea7 100644
--- a/litellm/integrations/custom_logger.py
+++ b/litellm/integrations/custom_logger.py
@@ -4,7 +4,6 @@ import dotenv, os
 
 from litellm.proxy._types import UserAPIKeyAuth
 from litellm.caching import DualCache
-
 from typing import Literal, Union, Optional
 import traceback
 
@@ -64,8 +63,17 @@ class CustomLogger:  # https://docs.litellm.ai/docs/observability/custom_callbac
         user_api_key_dict: UserAPIKeyAuth,
         cache: DualCache,
         data: dict,
-        call_type: Literal["completion", "embeddings", "image_generation"],
-    ):
+        call_type: Literal[
+            "completion",
+            "text_completion",
+            "embeddings",
+            "image_generation",
+            "moderation",
+            "audio_transcription",
+        ],
+    ) -> Optional[
+        Union[Exception, str, dict]
+    ]:  # raise exception if invalid, return a str for the user to receive - if rejected, or return a modified dictionary for passing into litellm
         pass
 
     async def async_post_call_failure_hook(
diff --git a/litellm/proxy/_super_secret_config.yaml b/litellm/proxy/_super_secret_config.yaml
index 2195a077d3..8db3eea3e6 100644
--- a/litellm/proxy/_super_secret_config.yaml
+++ b/litellm/proxy/_super_secret_config.yaml
@@ -17,4 +17,12 @@ model_list:
       api_key: os.environ/AZURE_API_KEY # The `os.environ/` prefix tells litellm to read this from the env. See https://docs.litellm.ai/docs/simple_proxy#load-api-keys-from-vault
   
 router_settings:
-  enable_pre_call_checks: true
\ No newline at end of file
+  enable_pre_call_checks: true
+
+litellm_settings:
+  callbacks: ["detect_prompt_injection"]
+  prompt_injection_params:
+    heuristics_check: true
+    similarity_check: true
+    reject_as_response: true
+
diff --git a/litellm/proxy/_types.py b/litellm/proxy/_types.py
index b900b623be..492c222fe6 100644
--- a/litellm/proxy/_types.py
+++ b/litellm/proxy/_types.py
@@ -251,6 +251,10 @@ class LiteLLMPromptInjectionParams(LiteLLMBase):
     llm_api_name: Optional[str] = None
     llm_api_system_prompt: Optional[str] = None
     llm_api_fail_call_string: Optional[str] = None
+    reject_as_response: Optional[bool] = Field(
+        default=False,
+        description="Return rejected request error message as a string to the user. Default behaviour is to raise an exception.",
+    )
 
     @root_validator(pre=True)
     def check_llm_api_params(cls, values):
diff --git a/litellm/proxy/hooks/prompt_injection_detection.py b/litellm/proxy/hooks/prompt_injection_detection.py
index 896046e943..08dbedd8c8 100644
--- a/litellm/proxy/hooks/prompt_injection_detection.py
+++ b/litellm/proxy/hooks/prompt_injection_detection.py
@@ -146,6 +146,7 @@ class _OPTIONAL_PromptInjectionDetection(CustomLogger):
             try:
                 assert call_type in [
                     "completion",
+                    "text_completion",
                     "embeddings",
                     "image_generation",
                     "moderation",
@@ -192,6 +193,15 @@ class _OPTIONAL_PromptInjectionDetection(CustomLogger):
             return data
 
         except HTTPException as e:
+
+            if (
+                e.status_code == 400
+                and isinstance(e.detail, dict)
+                and "error" in e.detail
+                and self.prompt_injection_params is not None
+                and self.prompt_injection_params.reject_as_response
+            ):
+                return e.detail["error"]
             raise e
         except Exception as e:
             traceback.print_exc()
diff --git a/litellm/proxy/proxy_server.py b/litellm/proxy/proxy_server.py
index 351984c2b8..d498638e33 100644
--- a/litellm/proxy/proxy_server.py
+++ b/litellm/proxy/proxy_server.py
@@ -124,6 +124,7 @@ from litellm.proxy.auth.auth_checks import (
     get_actual_routes,
 )
 from litellm.llms.custom_httpx.httpx_handler import HTTPHandler
+from litellm.exceptions import RejectedRequestError
 
 try:
     from litellm._version import version
@@ -3763,8 +3764,8 @@ async def chat_completion(
 
         data["litellm_logging_obj"] = logging_obj
 
-        ### CALL HOOKS ### - modify incoming data before calling the model
-        data = await proxy_logging_obj.pre_call_hook(
+        ### CALL HOOKS ### - modify/reject incoming data before calling the model
+        data = await proxy_logging_obj.pre_call_hook(  # type: ignore
             user_api_key_dict=user_api_key_dict, data=data, call_type="completion"
         )
 
@@ -3879,6 +3880,40 @@ async def chat_completion(
         )
 
         return response
+    except RejectedRequestError as e:
+        _data = e.request_data
+        _data["litellm_status"] = "fail"  # used for alerting
+        await proxy_logging_obj.post_call_failure_hook(
+            user_api_key_dict=user_api_key_dict,
+            original_exception=e,
+            request_data=_data,
+        )
+        _chat_response = litellm.ModelResponse()
+        _chat_response.choices[0].message.content = e.message  # type: ignore
+
+        if data.get("stream", None) is not None and data["stream"] == True:
+            _iterator = litellm.utils.ModelResponseIterator(
+                model_response=_chat_response, convert_to_delta=True
+            )
+            _streaming_response = litellm.CustomStreamWrapper(
+                completion_stream=_iterator,
+                model=data.get("model", ""),
+                custom_llm_provider="cached_response",
+                logging_obj=data.get("litellm_logging_obj", None),
+            )
+            selected_data_generator = select_data_generator(
+                response=_streaming_response,
+                user_api_key_dict=user_api_key_dict,
+                request_data=_data,
+            )
+
+            return StreamingResponse(
+                selected_data_generator,
+                media_type="text/event-stream",
+            )
+        _usage = litellm.Usage(prompt_tokens=0, completion_tokens=0, total_tokens=0)
+        _chat_response.usage = _usage  # type: ignore
+        return _chat_response
     except Exception as e:
         data["litellm_status"] = "fail"  # used for alerting
         traceback.print_exc()
@@ -3993,8 +4028,8 @@ async def completion(
             data["model"] = litellm.model_alias_map[data["model"]]
 
         ### CALL HOOKS ### - modify incoming data before calling the model
-        data = await proxy_logging_obj.pre_call_hook(
-            user_api_key_dict=user_api_key_dict, data=data, call_type="completion"
+        data = await proxy_logging_obj.pre_call_hook(  # type: ignore
+            user_api_key_dict=user_api_key_dict, data=data, call_type="text_completion"
         )
 
         ### ROUTE THE REQUESTs ###
@@ -4077,6 +4112,46 @@ async def completion(
         )
 
         return response
+    except RejectedRequestError as e:
+        _data = e.request_data
+        _data["litellm_status"] = "fail"  # used for alerting
+        await proxy_logging_obj.post_call_failure_hook(
+            user_api_key_dict=user_api_key_dict,
+            original_exception=e,
+            request_data=_data,
+        )
+        if _data.get("stream", None) is not None and _data["stream"] == True:
+            _chat_response = litellm.ModelResponse()
+            _usage = litellm.Usage(
+                prompt_tokens=0,
+                completion_tokens=0,
+                total_tokens=0,
+            )
+            _chat_response.usage = _usage  # type: ignore
+            _chat_response.choices[0].message.content = e.message  # type: ignore
+            _iterator = litellm.utils.ModelResponseIterator(
+                model_response=_chat_response, convert_to_delta=True
+            )
+            _streaming_response = litellm.TextCompletionStreamWrapper(
+                completion_stream=_iterator,
+                model=_data.get("model", ""),
+            )
+
+            selected_data_generator = select_data_generator(
+                response=_streaming_response,
+                user_api_key_dict=user_api_key_dict,
+                request_data=data,
+            )
+
+            return StreamingResponse(
+                selected_data_generator,
+                media_type="text/event-stream",
+                headers={},
+            )
+        else:
+            _response = litellm.TextCompletionResponse()
+            _response.choices[0].text = e.message
+            return _response
     except Exception as e:
         data["litellm_status"] = "fail"  # used for alerting
         await proxy_logging_obj.post_call_failure_hook(
diff --git a/litellm/proxy/utils.py b/litellm/proxy/utils.py
index 6b52eaddc6..d306624c9a 100644
--- a/litellm/proxy/utils.py
+++ b/litellm/proxy/utils.py
@@ -18,8 +18,18 @@ from litellm.llms.custom_httpx.httpx_handler import HTTPHandler
 from litellm.proxy.hooks.parallel_request_limiter import (
     _PROXY_MaxParallelRequestsHandler,
 )
+from litellm.exceptions import RejectedRequestError
 from litellm._service_logger import ServiceLogging, ServiceTypes
-from litellm import ModelResponse, EmbeddingResponse, ImageResponse
+from litellm import (
+    ModelResponse,
+    EmbeddingResponse,
+    ImageResponse,
+    TranscriptionResponse,
+    TextCompletionResponse,
+    CustomStreamWrapper,
+    TextCompletionStreamWrapper,
+)
+from litellm.utils import ModelResponseIterator
 from litellm.proxy.hooks.max_budget_limiter import _PROXY_MaxBudgetLimiter
 from litellm.proxy.hooks.tpm_rpm_limiter import _PROXY_MaxTPMRPMLimiter
 from litellm.proxy.hooks.cache_control_check import _PROXY_CacheControlCheck
@@ -32,6 +42,7 @@ from email.mime.text import MIMEText
 from email.mime.multipart import MIMEMultipart
 from datetime import datetime, timedelta
 from litellm.integrations.slack_alerting import SlackAlerting
+from typing_extensions import overload
 
 
 def print_verbose(print_statement):
@@ -182,18 +193,20 @@ class ProxyLogging:
             )
             litellm.utils.set_callbacks(callback_list=callback_list)
 
+    # The actual implementation of the function
     async def pre_call_hook(
         self,
         user_api_key_dict: UserAPIKeyAuth,
         data: dict,
         call_type: Literal[
             "completion",
+            "text_completion",
             "embeddings",
             "image_generation",
             "moderation",
             "audio_transcription",
         ],
-    ):
+    ) -> dict:
         """
         Allows users to modify/reject the incoming request to the proxy, without having to deal with parsing Request body.
 
@@ -220,8 +233,25 @@ class ProxyLogging:
                         call_type=call_type,
                     )
                     if response is not None:
-                        data = response
-
+                        if isinstance(response, Exception):
+                            raise response
+                        elif isinstance(response, dict):
+                            data = response
+                        elif isinstance(response, str):
+                            if (
+                                call_type == "completion"
+                                or call_type == "text_completion"
+                            ):
+                                raise RejectedRequestError(
+                                    message=response,
+                                    model=data.get("model", ""),
+                                    llm_provider="",
+                                    request_data=data,
+                                )
+                            else:
+                                raise HTTPException(
+                                    status_code=400, detail={"error": response}
+                                )
             print_verbose(f"final data being sent to {call_type} call: {data}")
             return data
         except Exception as e:
diff --git a/litellm/utils.py b/litellm/utils.py
index a265dbce43..30411ef03c 100644
--- a/litellm/utils.py
+++ b/litellm/utils.py
@@ -6492,6 +6492,7 @@ def get_formatted_prompt(
         "image_generation",
         "audio_transcription",
         "moderation",
+        "text_completion",
     ],
 ) -> str:
     """
@@ -6504,6 +6505,8 @@ def get_formatted_prompt(
         for m in data["messages"]:
             if "content" in m and isinstance(m["content"], str):
                 prompt += m["content"]
+    elif call_type == "text_completion":
+        prompt = data["prompt"]
     elif call_type == "embedding" or call_type == "moderation":
         if isinstance(data["input"], str):
             prompt = data["input"]
@@ -12246,3 +12249,34 @@ def _add_key_name_and_team_to_alert(request_info: str, metadata: dict) -> str:
         return request_info
     except:
         return request_info
+
+
+class ModelResponseIterator:
+    def __init__(self, model_response: ModelResponse, convert_to_delta: bool = False):
+        if convert_to_delta == True:
+            self.model_response = ModelResponse(stream=True)
+            _delta = self.model_response.choices[0].delta  # type: ignore
+            _delta.content = model_response.choices[0].message.content  # type: ignore
+        else:
+            self.model_response = model_response
+        self.is_done = False
+
+    # Sync iterator
+    def __iter__(self):
+        return self
+
+    def __next__(self):
+        if self.is_done:
+            raise StopIteration
+        self.is_done = True
+        return self.model_response
+
+    # Async iterator
+    def __aiter__(self):
+        return self
+
+    async def __anext__(self):
+        if self.is_done:
+            raise StopAsyncIteration
+        self.is_done = True
+        return self.model_response