Do new potential employers have the right to call your present employer for reference?

Employer has responsibility on recruitment process to keep the information as confidential for the candidates. If the employer confirms to recruit the cndidate then communicate to Supervisor, otherwise it deviates the confidentiality.

if u write his/her No. as refrence for sure there is nor prob. at a time

but if he/she called behind ur back it's not acceptabale at all