In a letter to party President Rajnath Singh, Jethmalani said he has been out of the BJP at least from 2004.
"I have been out of the party at least from 2004, if not earlier. In 2010, the party approached me with a request to join. At that time, I made it very clear that the party knows my views on all problems facing the nation. The party has no right to change me but I have the right to change it," he said.
Jethmalani, who had been critical of the BJP leadership and had revolted against the then party chief Nitin Gadkari, was on Tuesday expelled from the primary membership of the party for six years on charges of "breach of discipline".
He slammed the party for not referring to the letters written by him even before the expulsion notice was issued and those written on more than one occasion after the actual service of the show cause notice in November, 2012.
"This itself shows that there is no cause of expulsion... I have pointed out that disciplinary powers under the constitution are vested in the Disciplinary Committee. You do not have a Disciplinary Committee. Your action shows incompetence and contempt for law," he said.
In a strongly-worded letter, the 89-year-old Rajya Sabha member said "by this stupid order of expulsion, the party has committed suicide. "It will only bring joy to our corrupt rulers and few of their corrupt collaborators within the party. If you are determined to commit suicide, even the gods cannot salvage you."
Jethmalani, who is abroad on a vacation, said he would release the letters he had written to the party in the coming days.