diff --git a/pkg/scd/operational_intents_handler.go b/pkg/scd/operational_intents_handler.go
index e8e4d6e53..714f14325 100644
--- a/pkg/scd/operational_intents_handler.go
+++ b/pkg/scd/operational_intents_handler.go
@@ -455,6 +455,17 @@ func validateAndReturnUpsertParams(
 		}
 	}
 
+    if params.NewSubscription != nil {
+        // The spec states that NewSubscription.UssBaseUrl is required and an empty value
+        // makes no sense, so we will fail if an implicit subscription is requested but the base url is empty
+        if params.NewSubscription.UssBaseUrl == "" {
+            return nil, stacktrace.NewError("Missing required USS base url for new subscription (in parameters for implicit subscription)")
+        }
+        if params.SubscriptionId != nil {
+            return nil, stacktrace.NewError("Cannot provide both a Subscription ID and request an implicit subscription")
+        }
+    }
+
 	// Check if a subscription is required for this request:
 	// OIRs in an accepted state do not need a subscription.
 	if valid.state.RequiresSubscription() &&