diff --git a/bigchaindb/voting.py b/bigchaindb/voting.py
new file mode 100644
index 00000000..0138e783
--- /dev/null
+++ b/bigchaindb/voting.py
@@ -0,0 +1,47 @@
+import collections
+
+
+def filter_eligible_votes(votes, block_voters, keyring, check_signature):
+    """
+    Filter votes from unknown nodes or nodes that are not listed on
+    block. Here is our sybill protection.
+    """
+    eligible_voters = set(keyring) & set(block_voters)
+    eligible_votes = []
+
+    for vote in votes:
+        pubkey = vote['node_pubkey']
+        voter_eligible = pubkey in eligible_voters
+        sig_legit = sig_is_legit(vote)
+        if voter_eligible and sig_legit:
+            eligible_votes[pubkey].append(vote)
+
+    return eligible_votes
+
+
+def count_votes(eligible_votes, check_schema):
+    by_voter = collections.defaultdict(list)
+    for vote in eligible_votes:
+        by_voter[vote['node_pubkey']].append(vote)
+
+    n_valid = 0
+    n_invalid = 0
+    prev_blocks = collections.Counter()
+
+    for pubkey, votes in by_voter.items():
+        if len(votes) > 1 or not schema_is_correct(votes[0]):
+            n_invalid += 1
+            continue
+
+        vote = votes[0]
+        prev_blocks[vote['vote']['previous_block']] += 1
+        if vote['vote']['is_block_valid']:
+            n_valid += 1
+        else:
+            n_invalid += 1
+
+    return {
+        'valid': n_valid,
+        'invalid': n_invalid,
+        'prev_block': prev_blocks.most_common()[0]
+    }