diff --git a/advlabdb/adminModelViews.py b/advlabdb/adminModelViews.py
index f318ba5..c6dd50f 100644
--- a/advlabdb/adminModelViews.py
+++ b/advlabdb/adminModelViews.py
@@ -261,17 +261,18 @@ class UserView(SecureAdminModelView):
 class SemesterView(SecureAdminModelView):
     class CreateForm(Form):
         def defaultFormLabel():
-            if current_user.active_semester.label == "WS":
+            last_semester = Semester.lastSemester()
+            if last_semester.label == "WS":
                 return "SS"
             else:
                 return "WS"
 
         def defaultFormYear():
-            activeSemester = current_user.active_semester
-            if activeSemester.label == "WS":
-                return activeSemester.year + 1
+            last_semester = Semester.lastSemester()
+            if last_semester.label == "WS":
+                return last_semester.year + 1
             else:
-                return activeSemester.year
+                return last_semester.year
 
         label = RadioField(
             "Semester",
diff --git a/advlabdb/models.py b/advlabdb/models.py
index 1e77644..07c9332 100644
--- a/advlabdb/models.py
+++ b/advlabdb/models.py
@@ -455,7 +455,14 @@ class Semester(db.Model):
 
     __table_args__ = (db.UniqueConstraint(label, year),)
 
-    # TODO: def __init__(self, label, year):
+    def __init__(self, label, year):
+        last_semester = Semester.lastSemester()
+
+        if last_semester is not None:
+            if year < last_semester.year or (year == last_semester.year and label == "SS"):
+                raise DataBaseException(f"You can only create semesters older than the last semester {last_semester}!")
+
+        super().__init__(label=label, year=year)
 
     def initFromOldSemester(label, year, oldSemester, transferParts, transferAssistants):
         semester = Semester(label=label, year=year)