diff --git a/src/causalrl/identification/decision.py b/src/causalrl/identification/decision.py
index 399d781..f56fb34 100644
--- a/src/causalrl/identification/decision.py
+++ b/src/causalrl/identification/decision.py
@@ -43,6 +43,9 @@ class DecisionCertificate(NamedTuple):
     msm_certified: bool | None  # MSM layer robust to gamma_max? None if the MSM layer did not run
     summary: str
 
+    def __str__(self) -> str:
+        return self.summary
+
 
 def certify_decision(
     outcomes: Sequence[float],
diff --git a/tests/test_certify_decision.py b/tests/test_certify_decision.py
index 361a123..391cef9 100644
--- a/tests/test_certify_decision.py
+++ b/tests/test_certify_decision.py
@@ -107,6 +107,11 @@ def test_summary_is_human_readable(self):
         assert isinstance(summary, str) and summary
         assert "prefer treated" in summary
 
+    def test_str_returns_summary(self):
+        y, f, z = _confounded_rows(100, 0.0)
+        cert = certify_decision(y, f, confounder_bins=z)
+        assert str(cert) == cert.summary
+
     def test_requires_some_evidence(self):
         y, f, _ = _confounded_rows(200, 0.0)
         with pytest.raises(ValueError, match=r"confounder_bins|mi_cap|propensities"):