diff --git a/src/blenderbim/blenderbim/core/system.py b/src/blenderbim/blenderbim/core/system.py
index 1e5b026046..8015825f1b 100644
--- a/src/blenderbim/blenderbim/core/system.py
+++ b/src/blenderbim/blenderbim/core/system.py
@@ -59,7 +59,7 @@ def assign_system(ifc, system=None, product=None):
 
 
 def unassign_system(ifc, system=None, product=None):
-    ifc.run("system.unassign_system", product=product, system=system)
+    ifc.run("system.unassign_system", products=[product], system=system)
 
 
 def select_system_products(system_tool, system=None):
diff --git a/src/blenderbim/test/core/test_system.py b/src/blenderbim/test/core/test_system.py
index 82ef966b5c..51c4dc9bae 100644
--- a/src/blenderbim/test/core/test_system.py
+++ b/src/blenderbim/test/core/test_system.py
@@ -80,7 +80,7 @@ class TestAssignSystem:
 
 class TestUnassignSystem:
     def test_run(self, ifc):
-        ifc.run("system.unassign_system", product="product", system="system").should_be_called()
+        ifc.run("system.unassign_system", products=["product"], system="system").should_be_called()
         subject.unassign_system(ifc, system="system", product="product")
 
 
diff --git a/src/ifcopenshell-python/ifcopenshell/api/__init__.py b/src/ifcopenshell-python/ifcopenshell/api/__init__.py
index 10ade30ab8..9748c848a9 100644
--- a/src/ifcopenshell-python/ifcopenshell/api/__init__.py
+++ b/src/ifcopenshell-python/ifcopenshell/api/__init__.py
@@ -82,6 +82,9 @@ ARGUMENTS_DEPRECATION = {
     "system.assign_system": partial(
         batching_argument_deprecation, prev_argument="product", new_argument="products"
     ),
+    "system.unassign_system": partial(
+        batching_argument_deprecation, prev_argument="product", new_argument="products"
+    ),
 }
 
 
diff --git a/src/ifcopenshell-python/ifcopenshell/api/system/unassign_system.py b/src/ifcopenshell-python/ifcopenshell/api/system/unassign_system.py
index 10383ffbbb..121939a251 100644
--- a/src/ifcopenshell-python/ifcopenshell/api/system/unassign_system.py
+++ b/src/ifcopenshell-python/ifcopenshell/api/system/unassign_system.py
@@ -22,11 +22,16 @@ import ifcopenshell.util.element
 
 
 class Usecase:
-    def __init__(self, file, product=None, system=None):
-        """Unassigns a product from a system
+    def __init__(
+        self,
+        file: ifcopenshell.entity_instance,
+        products: list[ifcopenshell.entity_instance],
+        system: ifcopenshell.entity_instance,
+    ):
+        """Unassigns list of products from a system
 
-        :param product: The IfcDistributionElement to unassign from the system.
-        :type product: ifcopenshell.entity_instance.entity_instance
+        :param products: The list of IfcDistributionElements to unassign from the system.
+        :type products: list[ifcopenshell.entity_instance.entity_instance]
         :param system: The IfcSystem you want to unassign the element from.
         :type system: ifcopenshell.entity_instance.entity_instance
         :return: None
@@ -47,25 +52,15 @@ class Usecase:
             ifcopenshell.api.run("system.assign_system", model, products=[duct], system=system)
 
             # Not anymore!
-            ifcopenshell.api.run("system.unassign_system", model, product=duct, system=system)
+            ifcopenshell.api.run("system.unassign_system", model, products=[duct], system=system)
         """
         self.file = file
         self.settings = {
-            "product": product,
+            "products": products,
             "system": system,
         }
 
     def execute(self):
-        if not self.settings["system"].IsGroupedBy:
-            return
-        rel = self.settings["system"].IsGroupedBy[0]
-        related_objects = set(rel.RelatedObjects) or set()
-        related_objects.remove(self.settings["product"])
-        if len(related_objects):
-            rel.RelatedObjects = list(related_objects)
-            ifcopenshell.api.run("owner.update_owner_history", self.file, **{"element": rel})
-        else:
-            history = rel.OwnerHistory
-            self.file.remove(rel)
-            if history:
-                ifcopenshell.util.element.remove_deep2(self.file, history)
+        ifcopenshell.api.run(
+            "group.unassign_group", self.file, products=self.settings["products"], group=self.settings["system"]
+        )
diff --git a/src/ifcopenshell-python/test/api/system/test_unassign_system.py b/src/ifcopenshell-python/test/api/system/test_unassign_system.py
new file mode 100644
index 0000000000..1bf3433825
--- /dev/null
+++ b/src/ifcopenshell-python/test/api/system/test_unassign_system.py
@@ -0,0 +1,40 @@
+# IfcOpenShell - IFC toolkit and geometry engine
+# Copyright (C) 2022 Dion Moult <dion@thinkmoult.com>
+#
+# This file is part of IfcOpenShell.
+#
+# IfcOpenShell is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# IfcOpenShell is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with IfcOpenShell.  If not, see <http://www.gnu.org/licenses/>.
+
+import pytest
+import test.bootstrap
+import ifcopenshell.api
+import ifcopenshell.util.system
+
+
+class TestUnassignSystem(test.bootstrap.IFC4):
+    def test_unassign_system(self):
+        element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcFlowSegment")
+        element2 = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcFlowSegment")
+        element3 = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcFlowSegment")
+        system = ifcopenshell.api.run("system.add_system", self.file)
+        ifcopenshell.api.run("system.assign_system", self.file, products=[element, element2, element3], system=system)
+        ifcopenshell.api.run("system.unassign_system", self.file, products=[element2, element3], system=system)
+        assert ifcopenshell.util.system.get_system_elements(system) == [element]
+
+        ifcopenshell.api.run("system.unassign_system", self.file, products=[element], system=system)
+        assert ifcopenshell.util.system.get_system_elements(system) == []
+
+
+class TestUnassignSystemIFC2X3(test.bootstrap.IFC2X3, TestUnassignSystem):
+    pass
diff --git a/src/ifcopenshell-python/test/api/test_api.py b/src/ifcopenshell-python/test/api/test_api.py
index 458691cc56..acd375b203 100644
--- a/src/ifcopenshell-python/test/api/test_api.py
+++ b/src/ifcopenshell-python/test/api/test_api.py
@@ -19,6 +19,7 @@
 import test.bootstrap
 import ifcopenshell.api
 import ifcopenshell.util.element
+import ifcopenshell.util.system
 from datetime import datetime
 
 
@@ -151,3 +152,15 @@ class TestTemporarySupportForDeprecatedAPIArguments(test.bootstrap.IFC4):
         rel = rels[0]
         assert rel.RelatingGroup == system
         assert rel.RelatedObjects == (element,)
+
+    @deprecation_check
+    def test_unassign_system(self):
+        element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcFlowSegment")
+        element2 = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcFlowSegment")
+        system = ifcopenshell.api.run("system.add_system", self.file)
+        ifcopenshell.api.run("system.assign_system", self.file, products=[element, element2], system=system)
+        ifcopenshell.api.run("system.unassign_system", self.file, product=element, system=system)
+        assert ifcopenshell.util.system.get_system_elements(system) == [element2]
+
+        ifcopenshell.api.run("system.unassign_system", self.file, product=element2, system=system)
+        assert ifcopenshell.util.system.get_system_elements(system) == []