diff --git a/merkletree/pad.go b/merkletree/pad.go
index 02d8d9b..bb31951 100644
--- a/merkletree/pad.go
+++ b/merkletree/pad.go
@@ -26,7 +26,7 @@ type PAD struct {
 
 // NewPAD creates new PAD consisting of an array of hash chain
 // indexed by the epoch and its maximum length is len
-func NewPAD(policies Policies, signKey sign.PrivateKey, len uint64) (*PAD, error) {
+func NewPAD(policies *Policies, signKey sign.PrivateKey, len uint64) (*PAD, error) {
 	if policies == nil {
 		panic(ErrorNilPolicies)
 	}
@@ -37,15 +37,14 @@ func NewPAD(policies Policies, signKey sign.PrivateKey, len uint64) (*PAD, error
 	if err != nil {
 		return nil, err
 	}
-	pad.policies = policies
+	pad.policies = *policies
 	pad.snapshots = make(map[uint64]*SignedTreeRoot, len)
 	pad.loadedEpochs = make([]uint64, 0, len)
 	pad.updateInternal(nil, 0)
 	return pad, nil
 }
 
-// if policies is nil, the previous policies will be used
-func (pad *PAD) signTreeRoot(m *MerkleTree, epoch uint64) {
+func (pad *PAD) signTreeRoot(epoch uint64) {
 	var prevHash []byte
 	if pad.latestSTR == nil {
 		var err error
@@ -57,30 +56,29 @@ func (pad *PAD) signTreeRoot(m *MerkleTree, epoch uint64) {
 	} else {
 		prevHash = crypto.Digest(pad.latestSTR.Signature)
 	}
+	pad.tree.recomputeHash()
+	m := pad.tree.Clone()
 	pad.latestSTR = NewSTR(pad.signKey, pad.policies, m, epoch, prevHash)
 }
 
-func (pad *PAD) updateInternal(policies Policies, epoch uint64) {
-	pad.tree.recomputeHash()
-	m := pad.tree.Clone()
+func (pad *PAD) updateInternal(policies *Policies, epoch uint64) {
 	// create STR with the policies that were actually used in the prev.
 	// Set() operation
-	pad.signTreeRoot(m, epoch)
+	pad.signTreeRoot(epoch)
 	pad.snapshots[epoch] = pad.latestSTR
 	pad.loadedEpochs = append(pad.loadedEpochs, epoch)
-
 	if policies != nil { // update the policies if necessary
 		vrfKeyChanged := 1 != subtle.ConstantTimeCompare(
-			pad.policies.vrfPrivate(),
-			policies.vrfPrivate())
-		pad.policies = policies
+			pad.policies.vrfPrivateKey,
+			policies.vrfPrivateKey)
+		pad.policies = *policies
 		if vrfKeyChanged {
 			pad.reshuffle()
 		}
 	}
 }
 
-func (pad *PAD) Update(policies Policies) {
+func (pad *PAD) Update(policies *Policies) {
 	// delete older str(s) as needed
 	if len(pad.loadedEpochs) == cap(pad.loadedEpochs) {
 		n := cap(pad.loadedEpochs) / 2
@@ -89,12 +87,11 @@ func (pad *PAD) Update(policies Policies) {
 		}
 		pad.loadedEpochs = append(pad.loadedEpochs[:0], pad.loadedEpochs[n:]...)
 	}
-
 	pad.updateInternal(policies, pad.latestSTR.Epoch+1)
 }
 
 func (pad *PAD) Set(name string, value []byte) error {
-	index, _ := pad.computePrivateIndex(name, pad.policies.vrfPrivate())
+	index, _ := pad.computePrivateIndex(name, pad.policies.vrfPrivateKey)
 	return pad.tree.Set(index, name, value)
 }
 
@@ -107,7 +104,7 @@ func (pad *PAD) LookupInEpoch(name string, epoch uint64) (*AuthenticationPath, e
 	if str == nil {
 		return nil, ErrorSTRNotFound
 	}
-	lookupIndex, proof := pad.computePrivateIndex(name, str.Policies.vrfPrivate())
+	lookupIndex, proof := pad.computePrivateIndex(name, str.Policies.vrfPrivateKey)
 	ap := str.tree.Get(lookupIndex)
 	ap.VrfProof = proof
 	return ap, nil
@@ -125,7 +122,7 @@ func (pad *PAD) LatestSTR() *SignedTreeRoot {
 }
 
 func (pad *PAD) TB(name string, value []byte) (*TemporaryBinding, error) {
-	index, _ := pad.computePrivateIndex(name, pad.policies.vrfPrivate())
+	index, _ := pad.computePrivateIndex(name, pad.policies.vrfPrivateKey)
 	tb := NewTB(pad.signKey, pad.latestSTR.Signature, index, value)
 	err := pad.tree.Set(index, name, value)
 	return tb, err
@@ -142,7 +139,7 @@ func (pad *PAD) reshuffle() {
 		panic(err)
 	}
 	pad.tree.visitLeafNodes(func(n *userLeafNode) {
-		newIndex, _ := pad.computePrivateIndex(n.key, pad.policies.vrfPrivate())
+		newIndex, _ := pad.computePrivateIndex(n.key, pad.policies.vrfPrivateKey)
 		if err := newTree.Set(newIndex, n.key, n.value); err != nil {
 			panic(err)
 		}
diff --git a/merkletree/policy.go b/merkletree/policy.go
index 36b8713..d119a9f 100644
--- a/merkletree/policy.go
+++ b/merkletree/policy.go
@@ -8,55 +8,35 @@ import (
 
 type TimeStamp uint64
 
-type Policies interface {
-	EpDeadline() TimeStamp
-	Serialize() []byte
-	vrfPrivate() vrf.PrivateKey
-}
-
-type ConiksPolicies struct {
+type Policies struct {
 	LibVersion    string
 	HashID        string
 	vrfPrivateKey vrf.PrivateKey
-	VrfPubKey     []byte
+	VrfPublicKey  vrf.PublicKey
 	EpochDeadline TimeStamp
 }
 
-var _ Policies = (*ConiksPolicies)(nil)
-
-func NewPolicies(epDeadline TimeStamp, vrfPrivKey vrf.PrivateKey) Policies {
+func NewPolicies(epDeadline TimeStamp, vrfPrivKey vrf.PrivateKey) *Policies {
 	vrfPublicKey, ok := vrfPrivKey.Public()
 	if !ok {
 		panic(vrf.ErrorGetPubKey)
 	}
-	return &ConiksPolicies{
+	return &Policies{
 		LibVersion:    Version,
 		HashID:        crypto.HashID,
 		vrfPrivateKey: vrfPrivKey,
-		VrfPubKey:     vrfPublicKey,
+		VrfPublicKey:  vrfPublicKey,
 		EpochDeadline: epDeadline,
 	}
 }
 
 // Serialize encodes the policy to a byte array with the following format:
 // [lib version, cryptographic algorithm in use, epoch deadline, vrf public key]
-func (p *ConiksPolicies) Serialize() []byte {
-	vrfPublicKey, ok := p.vrfPrivateKey.Public()
-	if !ok {
-		panic(vrf.ErrorGetPubKey)
-	}
+func (p *Policies) Serialize() []byte {
 	var bs []byte
 	bs = append(bs, []byte(p.LibVersion)...)                       // lib Version
 	bs = append(bs, []byte(p.HashID)...)                           // cryptographic algorithms in use
 	bs = append(bs, util.ULongToBytes(uint64(p.EpochDeadline))...) // epoch deadline
-	bs = append(bs, vrfPublicKey...)                               // vrf public key
+	bs = append(bs, p.VrfPublicKey...)                             // vrf public key
 	return bs
 }
-
-func (p *ConiksPolicies) vrfPrivate() vrf.PrivateKey {
-	return p.vrfPrivateKey
-}
-
-func (p *ConiksPolicies) EpDeadline() TimeStamp {
-	return p.EpochDeadline
-}
diff --git a/protocol/directory.go b/protocol/directory.go
index 3cf7684..63f13c2 100644
--- a/protocol/directory.go
+++ b/protocol/directory.go
@@ -12,7 +12,7 @@ type ConiksDirectory struct {
 	pad      *merkletree.PAD
 	useTBs   bool
 	tbs      map[string]*merkletree.TemporaryBinding
-	policies merkletree.Policies
+	policies *merkletree.Policies
 }
 
 func InitDirectory(epDeadline merkletree.TimeStamp, vrfKey vrf.PrivateKey,
@@ -44,7 +44,7 @@ func (d *ConiksDirectory) SetPolicies(epDeadline merkletree.TimeStamp, vrfKey vr
 }
 
 func (d *ConiksDirectory) EpochDeadline() merkletree.TimeStamp {
-	return d.pad.LatestSTR().Policies.EpDeadline()
+	return d.pad.LatestSTR().Policies.EpochDeadline
 }
 
 func (d *ConiksDirectory) LatestSTR() *merkletree.SignedTreeRoot {
diff --git a/protocol/directory_test.go b/protocol/directory_test.go
index 1f37c47..07a259d 100644
--- a/protocol/directory_test.go
+++ b/protocol/directory_test.go
@@ -316,3 +316,34 @@ func TestHandleOps(t *testing.T) {
 		t.Fatal("Expect error", ErrorMalformedClientMessage, "got", err)
 	}
 }
+
+func TestPoliciesChanges(t *testing.T) {
+	d := newDirectory(t, false)
+	if p := d.LatestSTR().Policies.EpochDeadline; p != 1 {
+		t.Fatal("Unexpected policies", "want", 1, "got", p)
+	}
+
+	// change the policies
+	vrfKey, err := vrf.GenerateKey(nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	d.SetPolicies(2, vrfKey)
+	d.Update()
+	// expect the policies doesn't change yet
+	if p := d.LatestSTR().Policies.EpochDeadline; p != 1 {
+		t.Fatal("Unexpected policies", "want", 1, "got", p)
+	}
+
+	d.Update()
+	// expect the new policies
+	if p := d.LatestSTR().Policies.EpochDeadline; p != 2 {
+		t.Fatal("Unexpected policies", "want", 2, "got", p)
+	}
+	p0 := d.pad.GetSTR(0).Policies.EpochDeadline
+	p1 := d.pad.GetSTR(1).Policies.EpochDeadline
+	p2 := d.pad.GetSTR(2).Policies.EpochDeadline
+	if p0 != 1 || p1 != 1 || p2 != 2 {
+		t.Fatal("Maybe the STR's policies were malformed")
+	}
+}