During a jury trial the presiding justice shall rule and charge the jury, orally or in writing, upon all matters of law arising in the case but shall not, during the trial, including the charge, express an opinion upon issues of fact arising in the case, and such an expression of opinion is sufficient cause for a new trial if either party aggrieved thereby and interested desires it, and the same shall be ordered accordingly by the law court on appeal in a civil or criminal case.   [PL 1965, c. 356, §11 (AMD).]