diff --git a/app/crud.py b/app/crud.py
index 0410986..dc90404 100644
--- a/app/crud.py
+++ b/app/crud.py
@@ -173,6 +173,12 @@ def _create_election_without_candidates_or_grade(
     params = election.model_dump()
     del params["candidates"]
     del params["grades"]
+    
+    if params.get("date_start") is not None and params.get("date_end") is not None:
+        if params["date_start"] >= params["date_end"]:
+            raise errors.ForbiddenError(
+                "The start date must be before the end date of the election"
+            )
 
     db_election = models.Election(**params)
     db.add(db_election)
@@ -283,6 +289,17 @@ def update_election(
     if db_election is None:
         raise errors.NotFoundError("elections")
 
+    if election.date_start is not None and election.date_end is None and db_election.date_end is not None:
+        if election.date_start > db_election.date_end:
+            raise errors.ForbiddenError(
+                "The start date must be before the end date of the election"
+            )
+    elif election.date_end is not None and election.date_start is None:
+        if election.date_end < db_election.date_start:
+            raise errors.ForbiddenError(
+                "The end date must be after the start date of the election"
+            )
+
     if (
         election.restricted is not None
         and bool(db_election.restricted) != election.restricted
diff --git a/app/main.py b/app/main.py
index 790dddb..08795ed 100644
--- a/app/main.py
+++ b/app/main.py
@@ -28,6 +28,16 @@
 async def main():
     return {"message": "Hello World"}
 
+@app.exception_handler(schemas.ArgumentsSchemaError)
+async def invalid_schema_exception_handler(
+    request: Request, exc: schemas.ArgumentsSchemaError
+):
+    return JSONResponse(
+        status_code=422,
+        content={
+            "message": f"Validation Error. {exc}",
+        },
+    )
 
 @app.exception_handler(errors.NotFoundError)
 async def not_found_exception_handler(request: Request, exc: errors.NotFoundError):
diff --git a/app/schemas.py b/app/schemas.py
index 6db2498..2d1e270 100644
--- a/app/schemas.py
+++ b/app/schemas.py
@@ -1,7 +1,8 @@
 import typing as t
+from typing_extensions import Self
 from datetime import datetime, timedelta, timezone
 import dateutil.parser
-from pydantic import BaseModel, Field, field_validator, ValidationInfo
+from pydantic import BaseModel, Field, field_validator, ValidationInfo, model_validator
 from pydantic_settings import SettingsConfigDict
 from .settings import settings
 
@@ -121,6 +122,13 @@ class ElectionBase(BaseModel):
     restricted: bool = False
     auth_for_result: bool = False
 
+    @model_validator(mode="after")
+    def check_dates_order(self) -> Self:
+        if self.date_start and self.date_end and _parse_date(self.date_start) > _parse_date(self.date_end):
+            raise ArgumentsSchemaError("date_start must be before or equal to date_end")
+        
+        return self
+
     @field_validator("date_end", "date_start", mode="before")
     @classmethod
     def parse_date(cls, value):
@@ -229,6 +237,13 @@ class ElectionUpdate(BaseModel):
     candidates: list[CandidateUpdate] | None = None
     auth_for_result: bool | None = None
 
+    @model_validator(mode="after")
+    def check_dates_order(self) -> Self:
+        if self.date_start and self.date_end and _parse_date(self.date_start) > _parse_date(self.date_end):
+            raise ArgumentsSchemaError(f"date_start must be before or equal to date_end")
+            
+        return self
+
     @field_validator("date_end", "date_start", mode="before")
     @classmethod
     def parse_date(cls, value):
diff --git a/app/tests/test_api.py b/app/tests/test_api.py
index 9330201..90c2420 100644
--- a/app/tests/test_api.py
+++ b/app/tests/test_api.py
@@ -111,6 +111,46 @@ def test_create_election():
     data = response.json()
     assert data["name"] == body["name"]
 
+def test_start_end_date_are_valid():
+    # cannot create an election where the start date is after the end date 
+    body = _random_election(2, 2)
+    body["date_start"] = (datetime.now() + timedelta(days=1)).isoformat()
+    body["date_end"] = (datetime.now()).isoformat()
+    response = client.post("/elections", json=body)
+    assert response.status_code == 422, response.text
+
+    body["date_start"] = (datetime.now()).isoformat()
+    body["date_end"] = (datetime.now() + timedelta(days=1)).isoformat()
+    response = client.post("/elections", json=body)
+    assert response.status_code == 200, response.text
+    election_data = response.json()
+    del election_data["candidates"]
+    del election_data["grades"]
+    del election_data["name"]
+    del election_data["restricted"]
+    del election_data["hide_results"]
+    del election_data["auth_for_result"]
+    admin_token = election_data["admin"]
+    election_ref = election_data["ref"]
+
+    # update election should not be allowed if the start date is after the end date
+    election_data["date_start"] = (datetime.now() + timedelta(days=1)).isoformat()
+    election_data["date_end"] = (datetime.now()).isoformat()
+    response = client.put("/elections", json=election_data, headers={"Authorization": f"Bearer {admin_token}"})
+    assert response.status_code == 422, response.text
+
+    # update election should be allowed if the start date is before the end date
+    del election_data["date_start"]
+    election_data["date_end"] = (datetime.now() - timedelta(days=1)).isoformat()
+    response = client.put("/elections", json=election_data, headers={"Authorization": f"Bearer {admin_token}"})
+    assert response.status_code == 403, response.text
+
+    # update election should be allowed if the start date is before the end date
+    del election_data["date_end"]
+    election_data["date_start"] = (datetime.now() + timedelta(days=2)).isoformat()
+    response = client.put("/elections", json=election_data, headers={"Authorization": f"Bearer {admin_token}"})
+    assert response.status_code == 403, response.text
+
 
 def test_get_election():
     body = _random_election(3, 4)
@@ -309,13 +349,14 @@ def test_cannot_create_vote_on_ended_election():
     """
     # Create a random election
     body = _random_election(10, 5)
+    body["date_start"] = (datetime.now() - timedelta(days=2)).isoformat()
     body["date_end"] = (datetime.now() - timedelta(days=1)).isoformat()
     response = client.post("/elections", json=body)
     election_data = response.json()
     assert response.status_code == 200, election_data
     assert len(election_data["invites"]) == 0
     election_ref = election_data["ref"]
-    ballot_token = election_data["admin"]
+    admin_token = election_data["admin"]
 
     # We create votes using the ID
     votes = _generate_votes_from_response("id", election_data)
@@ -330,7 +371,7 @@ def test_cannot_create_vote_on_ended_election():
     response = client.put(
         f"/elections",
         json={"force_close": True, "date_end":(datetime.now() + timedelta(days=1)).isoformat(), "ref": election_ref},
-        headers={"Authorization": f"Bearer {ballot_token}"},
+        headers={"Authorization": f"Bearer {admin_token}"},
     )
     assert response.status_code == 200, response.json()
 
@@ -386,10 +427,14 @@ def test_cannot_update_vote_on_ended_election():
     # Test for date_end in the past
     response = client.put(
         f"/elections",
-        json={"force_close": False, "date_end":(datetime.now() - timedelta(days=1)).isoformat(), "ref": election_ref},
+        json={"force_close": False, "date_start":(datetime.now() - timedelta(days=2)).isoformat(), "date_end":(datetime.now() - timedelta(days=1)).isoformat(), "ref": election_ref},
         headers={"Authorization": f"Bearer {election_token}"},
     )
 
+    assert response.status_code == 200, response.json()["date_end"]
+
+    print(response.json()["date_end"])
+
     response = client.put(
         f"/ballots",
         json={"votes": votes},