diff --git a/cads_adaptors/constraints.py b/cads_adaptors/constraints.py
index f3bb36ff..02b7db53 100644
--- a/cads_adaptors/constraints.py
+++ b/cads_adaptors/constraints.py
@@ -617,6 +617,8 @@ def legacy_intersect_constraints(
             }
 
     """
+    if constraints is None or len(constraints) == 0:
+        return [request]
     requests = []
     constraints = parse_constraints(constraints)
     constrained_fields = set(itertools.chain.from_iterable(constraints))
diff --git a/tests/test_10_constraints.py b/tests/test_10_constraints.py
index 15f2faba..d2bf91ca 100644
--- a/tests/test_10_constraints.py
+++ b/tests/test_10_constraints.py
@@ -379,3 +379,10 @@ def test_legacy_intersect_constraints():
     ]
     actual = constraints.legacy_intersect_constraints(request, raw_constraints)
     assert actual == expected
+
+
+def test_legacy_intersect_empty_constraints():
+    raw_constraints = []
+    request = {"foo": "bar"}
+    actual = constraints.legacy_intersect_constraints(request, raw_constraints)
+    assert actual == [{"foo": "bar"}]