In the trial of the case of a contested election, the parties shall be restricted to the grounds of objection in the specifications set forth and to the statement of the other grounds upon which the person declared to have been elected rests the validity of that person’s election and shall not examine into the illegality of any other vote than those specified as illegal nor impeach such votes for any causes other than those so specified.

18 Del. Laws, c. 22, § ?5; Code 1915, § ?1873; Code 1935, § ?1992; 15 Del. C. 1953, § ?5925; 70 Del. Laws, c. 186, § ?1;