diff --git a/cozo-core/src/data/expr.rs b/cozo-core/src/data/expr.rs
index fe379170..fb230b3b 100644
--- a/cozo-core/src/data/expr.rs
+++ b/cozo-core/src/data/expr.rs
@@ -895,6 +895,7 @@ pub(crate) fn get_op(name: &str) -> Option<&'static Op> {
         "rand_uuid_v1" => &OP_RAND_UUID_V1,
         "rand_uuid_v4" => &OP_RAND_UUID_V4,
         "uuid_timestamp" => &OP_UUID_TIMESTAMP,
+        "validity" => &OP_VALIDITY,
         "now" => &OP_NOW,
         "format_timestamp" => &OP_FORMAT_TIMESTAMP,
         "parse_timestamp" => &OP_PARSE_TIMESTAMP,
diff --git a/cozo-core/src/data/functions.rs b/cozo-core/src/data/functions.rs
index b973484d..e65a80bd 100644
--- a/cozo-core/src/data/functions.rs
+++ b/cozo-core/src/data/functions.rs
@@ -1780,9 +1780,7 @@ fn get_impl(args: &[DataValue]) -> Result<DataValue> {
                         .ok_or_else(|| miette!("index '{}' not found in json", i))?
                         .clone()
                 }
-                DataValue::List(l) => {
-                    get_json_path_immutable(json, l)?.clone()
-                }
+                DataValue::List(l) => get_json_path_immutable(json, l)?.clone(),
                 _ => bail!("second argument to 'get' mut be a string or integer"),
             };
             let res = json2val(res);
@@ -2526,3 +2524,21 @@ pub(crate) fn op_uuid_timestamp(args: &[DataValue]) -> Result<DataValue> {
         _ => bail!("not an UUID"),
     })
 }
+
+define_op!(OP_VALIDITY, 1, true);
+pub(crate) fn op_validity(args: &[DataValue]) -> Result<DataValue> {
+    let ts = args[0]
+        .get_int()
+        .ok_or_else(|| miette!("'validity' expects an integer"))?;
+    let is_assert = if args.len() == 1 {
+        true
+    } else {
+        args[1]
+            .get_bool()
+            .ok_or_else(|| miette!("'validity' expects a boolean as second argument"))?
+    };
+    Ok(DataValue::Validity(Validity {
+        timestamp: ValidityTs(Reverse(ts)),
+        is_assert: Reverse(is_assert),
+    }))
+}