diff --git a/crates/curp-external-api/src/conflict.rs b/crates/curp-external-api/src/conflict.rs
new file mode 100644
index 000000000..c80e8294c
--- /dev/null
+++ b/crates/curp-external-api/src/conflict.rs
@@ -0,0 +1,55 @@
+#![allow(clippy::module_name_repetitions)]
+
+/// Insert into speculative pool
+pub trait SpeculativePool {
+    /// Entry of the pool
+    type Entry;
+
+    /// Inserts a command in to the pool
+    ///
+    /// Returns `Some(Entry)` if a conflict is detected
+    fn insert(&mut self, entry: Self::Entry) -> Option<Self::Entry>;
+
+    /// Returns the number of commands in the pool
+    fn len(&self) -> usize;
+
+    /// Checks if the pool contains some commands that will conflict with all other commands
+    fn is_empty(&self) -> bool;
+
+    /// Removes a command from the pool
+    fn remove(&mut self, entry: Self::Entry);
+
+    /// Returns all commands in the pool
+    fn all(&self) -> Vec<Self::Entry>;
+
+    /// Clears all entries in the pool
+    fn clear(&mut self);
+}
+
+/// Insert into speculative pool
+pub trait UncommittedPool {
+    /// Entry of the pool
+    type Entry;
+    /// Inserts a command in to the pool
+    ///
+    /// Returns `true` if a conflict is detected
+    fn insert(&mut self, entry: Self::Entry) -> bool;
+
+    /// Returns all commands in the pool that conflicts with the given command
+    fn all_conflict(&self, entry: &Self::Entry) -> Vec<Self::Entry>;
+
+    /// Returns all commands in the pool
+    fn all(&self) -> Vec<Self::Entry>;
+
+    /// Returns the number of commands in the pool
+    fn len(&self) -> usize;
+
+    /// Checks if the pool will conflict with all commands
+    fn is_empty(&self) -> bool;
+
+    /// Removes a command from the pool
+    fn remove(&mut self, entry: Self::Entry);
+
+    /// Clears all entries in the pool
+    fn clear(&mut self);
+}
diff --git a/crates/curp-external-api/src/lib.rs b/crates/curp-external-api/src/lib.rs
index 73421d4ae..81d9bd3af 100644
--- a/crates/curp-external-api/src/lib.rs
+++ b/crates/curp-external-api/src/lib.rs
@@ -149,3 +149,6 @@ pub type InflightId = u64;
 pub mod cmd;
 /// The command to be executed
 pub mod role_change;
+
+/// Conflict trait
+pub mod conflict;