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 86e286f..da40aba 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
@@ -101,32 +101,39 @@ public final class AssertionImpl implements Assertion {
         CommonUtils.assertNotNull(this.attributes, "attributes cannot be null.");
     }
 
+    @Override
     public Date getAuthenticationDate() {
         return this.authenticationDate;
     }
 
+    @Override
     public Date getValidFromDate() {
         return this.validFromDate;
     }
 
+    @Override
     public Date getValidUntilDate() {
         return this.validUntilDate;
     }
 
+    @Override
     public Map<String, Object> getAttributes() {
         return this.attributes;
     }
 
+    @Override
     public AttributePrincipal getPrincipal() {
         return this.principal;
     }
 
+    @Override
     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));
+        return (this.validFromDate.before(now) || this.validFromDate.equals(now)) 
+                && (this.validUntilDate == null || this.validUntilDate.after(now) || this.validUntilDate.equals(now));
     }
 }
diff --git a/cas-client-core/src/test/java/org/jasig/cas/client/validation/AssertionImplTests.java b/cas-client-core/src/test/java/org/jasig/cas/client/validation/AssertionImplTests.java
index de6e856..335dbe6 100644
--- a/cas-client-core/src/test/java/org/jasig/cas/client/validation/AssertionImplTests.java
+++ b/cas-client-core/src/test/java/org/jasig/cas/client/validation/AssertionImplTests.java
@@ -18,6 +18,7 @@
  */
 package org.jasig.cas.client.validation;
 
+import java.util.Date;
 import java.util.HashMap;
 import java.util.Map;
 import junit.framework.TestCase;
@@ -49,6 +50,11 @@ public final class AssertionImplTests extends TestCase {
         assertNull(assertion.getPrincipal().getProxyTicketFor("test"));
     }
 
+    public void testAssertionValidity() throws Exception {
+        final Assertion assertion = new AssertionImpl(CONST_PRINCIPAL, new Date(), new Date(), new Date(), CONST_ATTRIBUTES);
+        assertTrue(assertion.isValid());
+    }
+    
     public void testCompleteConstructor() {
         final Assertion assertion = new AssertionImpl(CONST_PRINCIPAL, CONST_ATTRIBUTES);