delivered the opinion of the Court.
Benito Delgado Martinez was accused and convicted by the court of the offense of burglary in the first degree.
He assigns on appeal that his judgment is void because he did not waive expressly and intelligently his right to a trial by jury and because he was deprived of effective legal assistance.
1. The record on this matter shows the following:
“Judge:
Are the parties ready?
“Mr. Navarro:
We are ready.
“Prosecuting Attorney:
We are ready.
“Judge:
Is this case to be tried by a jury or by the court?
“Mr. Navarro:
By the court.
“Judge:
Colleague, did you speak with the defendant about his waiver?
“Mr. Navarro:
Yes, your Honor.
“Judge:
Are you Benito Delgado Martinez?
“Defendant:
Yes, sir.
“Judge:
Are you the defendant in this case ?
“Defendant:
Yes, sir.
“Judge:
Are you accused of burglary in the first degree?
“A. Yes, sir.
“Judge:
Your attorney has informed the court that you waive your right to a trial by jury and that you want the case to be tried by the court? Is that correct?
*706“A. Yes, sir.
“JUDGE:
You have not received any offer, nor threat, nor have been coerced to waive your right to a trial by jury?
“A. No, sir.
“Judge:
The court accepts as voluntary the waiver made by defendant of his right to a trial by jury, and the case will continue to be heard by the court.”
It is evident that the trial judge did not previously warn appellant what the waiver of the right to a trial by jury means. People v. Sierra Serrano, Judgment of March 19, 1968; People v. Juarbe de la Rosa, 95 P.R.R. 736, Judgment on reconsideration, February 21, 1968.
There is nothing in the record to show the circumstances, facts, or knowledge (1) on which appellant relied to answer that “he was conscious” of his waiver to the right to a trial by jury, or (2) to justify the trial judge in concluding that such answer was indicative that appellant knew the meaning and scope of the act of waiving the right to a trial by jury, and of the difference between being tried by the court and by the jury.
However, we do not find any reason to extend the pronouncement of Juarbe, supra, to cases prosecuted prior to that decision. Therefore, with respect to the waiver of the right to a trial by jury, it is available only to persons whose trials commenced after February 21, 1968, date of the judgment of Juarbe, supra. Contrary to what is alleged, it is in Juarbe where for the first time, in a positive and unambiguous manner, we held that the trial judge is bound to explain to the defendant the meaning of the waiver of the right to a trial by jury and to warn him of the consequences thereof. The isolated expressions contained in former cases did not have the scope which is sought to give them; the ratio, decidendi of these decisions centered on whether the waiver *707had been personally made by the defendant as required by Rule 111 of the Rules of Criminal Procedure. Insofar as the retroactive application of the decision in Juarbe is concerned, we are satisfied that as held in Roberts v. Russell, 392 U.S. 293 (decided June 10, 1968), it is not a rule of criminal procedure fashioned to correct serious flaws in the fact-finding process at trial and any departure therefrom does not affect the basis of a fair and impartial trial because the defendant was assured a fair determination of his guilt or innocence.1
Any doubt in this respect disappears in view of the action taken by the Federal Supreme Court on June 17, 1968 in Carcerano v. Gladden, 392 U.S. 631, refusing to extend the rule announced in Duncan v. Louisiana, 391 U.S. 145, and Bloom v. Illinois, 391 U.S. 194 — the right to jury trial in certain misdemeanor cases — to prosecutions where trials began prior to May 20,1968, date when these last two decisions were rendered.
2. The assignment of lack of legal assistance is based on the fact that the attorney who represented appellant during the trial did not appear at the time sentence was pronounced; that the court appointed another attorney to represent him then; that this attorney requested the court to reconsider his appointment as defendant’s counsel; and that the court denied said petition.
Appellant, however, has not shown that said attorney acted or failed to act in such a manner as to prejudice him, nor has he shown the prejudice he has suffered as a result of the court’s action, that is to say, that because appellant did not have effective legal assistance at that time, one or more of the causes enumerated in Rule 168. of the Rules of *708Criminal Procedure why sentence should not he pronounced in this case was not adduced. People v. Hernández, 94 P.R.R. 111 (1967).
In view of the foregoing, the judgment rendered in this case by the Superior Court, San Juan Part, on June 29, 1966, will be affirmed.
Mr. Justice Santana Becerra dissented in a separate opinion in which Mr. Justice Hernández Matos and Mr. Justice Dávila concur.—0—-
It should be borne in mind in that respect that until the approval of the Rules of Criminal Procedure of 1963, the defendant’s attorney could waive the right to a trial by jury. People v. Cabán Rosa, 92 P.R.R. 844 (1965).