Concept: The International Court of Justice is the principal judicial organ of the United Nations. Its composition and tenure of judges are governed by the Statute of the International Court of Justice.
Step 1: Check Statement A.
The International Court of Justice consists of 15 judges.
\[
A = \text{Correct}
\]
Step 2: Check Statement B.
Judges are not nominated by the Security Council. They are nominated by national groups in the Permanent Court of Arbitration and elected by the General Assembly and Security Council.
\[
B = \text{Incorrect}
\]
Step 3: Check Statement C.
Judges of the International Court of Justice hold office for a term of 9 years.
\[
C = \text{Correct}
\]
Step 4: Check Statement D.
Judges can be re-elected after expiry of their term.
\[
D = \text{Correct}
\]
Therefore, the correct statements are:
\[
A,\ C,\ D
\]