diff --git a/cas-client-core/src/main/java/org/jasig/cas/client/validation/Assertion.java b/cas-client-core/src/main/java/org/jasig/cas/client/validation/Assertion.java
index 1e835ee..1f51869 100644
--- a/cas-client-core/src/main/java/org/jasig/cas/client/validation/Assertion.java
+++ b/cas-client-core/src/main/java/org/jasig/cas/client/validation/Assertion.java
@@ -69,4 +69,12 @@ public interface Assertion extends Serializable {
      * @return the principal.
      */
     AttributePrincipal getPrincipal();
+
+    /**
+     * Determines whether an Assertion is considered usable or not.  A naive implementation may just check the date validity.
+     *
+     * @return true if its valid, false otherwise.
+     * @since 3.3.0 (though in 3.3.0, no one actually calls this)
+     */
+    boolean isValid();
 }
diff --git a/cas-client-core/src/main/java/org/jasig/cas/client/validation/AssertionImpl.java b/cas-client-core/src/main/java/org/jasig/cas/client/validation/AssertionImpl.java
index c15a6e3..d2612e7 100644
--- a/cas-client-core/src/main/java/org/jasig/cas/client/validation/AssertionImpl.java
+++ b/cas-client-core/src/main/java/org/jasig/cas/client/validation/AssertionImpl.java
@@ -121,4 +121,13 @@ public final class AssertionImpl implements Assertion {
     public AttributePrincipal getPrincipal() {
         return this.principal;
     }
+
+    public boolean isValid() {
+        if (this.validFromDate == null) {
+            return true;
+        }
+
+        final Date now = new Date();
+        return this.validFromDate.before(now) && (this.validUntilDate == null || this.validUntilDate.after(now));
+    }
 }