The Judicial Branch is the third branch of the United States’ government.  The first branch is legislature, or congress, which passes laws.  The second and executive branch enforces laws.  The judiciary holds the two prior branches in check by interpreting the laws passed by the legislature, determining their meaning and whether they are valid. Statutes are invalid if they are contrary to the United States Constitution.  Even those that are consistent with the constitution need to be interpreted and applied.  This is the job of the courts in the United States.