I dissent. Defendant was placed in jeopardy as to the underlying charges and the prior conviction allegations when the jury was sworn on March 7, 1990. When the jury was discharged on March 15, 1990, without deciding the issue of the truth of the prior conviction allegations, and without the consent of defendant or legal necessity, the prior conviction allegations could not be retried without offending the double jeopardy clauses of the state and federal Constitutions.
I also would find that it is not part of defendant’s burden to object when the People fail to try him on a part of the information. In our adversary system, it is the People’s burden to prove the charges, and it is not part of defendant’s burden to help the People meet their responsibility.
I
It is black letter law that “[ojnce jeopardy has attached, discharge of the jury without a verdict is tantamount to an acquittal and prevents a retrial, unless the defendant consented to the discharge or legal necessity required it.” (Stone v. Superior Court (1982) 31 Cal.3d 503, 516 [183 Cal.Rptr. 647, 646 P.2d 809]; Arizona v. Washington (1978) 434 U.S. 497, 503-505 [54 L.Ed.2d 717, 726-728, 98 S.Ct. 824].)
It is true that we should not engage in a purely mechanical analysis of when jeopardy attaches and terminates. The states have some freedom, as the majority opinion observes, in setting up procedures to separate or consolidate trial of charges in a criminal proceeding. (Maj. opn., ante, pp. 595-596.) But if under state law an allegation requires trial “with the hallmarks of the trial on guilt or innocence,” that is, before a jury with precise fact-finding *598duties to be carried out under a “beyond a reasonable doubt” standard in the same proceeding as the underlying criminal charges, then double jeopardy protections apply to trial of that allegation. (Bullington v. Missouri (1981) 451 U.S. 430, 438-439 [68 L.Ed.2d 270, 278-279, 101 S.Ct. 1852] [jeopardy attaches to life verdict in capital sentencing trial that bore hallmarks of trial on guilt or innocence]; see also Arizona v. Rumsey (1984) 467 U.S. 203, 209-211 [81 L.Ed.2d 164, 170-172, 104 S.Ct. 2305].)
We ourselves have said that jeopardy attaches to trial of sentence enhancement allegations when the jury is sworn to try the underlying offenses. (People v. Superior Court (Marks) (1991) 1 Cal.4th 56, 78, fn. 22 [2 Cal.Rptr.2d 389, 820 P.2d 613].)
Moreover, Penal Code section 1025 requires that the prior conviction allegation be tried in a unitary proceeding by the same jury that tries the underlying charges. This interpretation is long established. (People v. Kings-bury (1945) 70 Cal.App.2d 128, 131 [160 P.2d 587]; see also People v. Ysabel (1938) 28 Cal.App.2d 259, 263-264 [82 P.2d 476].) The accusatory pleading must allege the charged prior conviction (People v. Lo Cicero (1969) 71 Cal.2d 1186, 1192 [80 Cal.Rptr. 913, 459 P.2d 241]; Pen. Code, § 969), the accused has the right to have the allegation tried by a jury, and the proof beyond a reasonable doubt standard applies. (People v. Morton (1953) 41 Cal.2d 536, 539 [261 P.2d 523].) State law contemplates, obviously, that jeopardy attaches to the trial of the prior conviction allegation when the jury that is to try both the underlying charges and the prior conviction allegations is sworn.
Trial of the underlying charges and the prior conviction allegations was bifurcated. This does not mean that jeopardy did not attach as to the prior conviction allegations when the jury was sworn. As the Court of Appeal in People v. Wojahn (1984) 150 Cal.App.3d 1024, 1033 [198 Cal.Rptr. 277], properly observed, bifurcation separates issues in a trial, but it does not, unlike severance, produce two causes to be heard in two separate trials. (Id. at p. 1033; accord, People v. Givan (1992) 4 Cal.App.4th 1107, 1114-1115 [6 Cal.Rptr.2d 339].) That bifurcation separates issues rather than proceedings is clear from the determination of the court in People v. Givan, supra, 4 Cal.App.4th 1107, that the assertion of the right of self-representation is untimely if made for the first time in a bifurcated trial when the jury takes up the issue of the prior conviction allegations.
Here, jeopardy attached to trial of the prior conviction allegations on March 7, 1990. The jury was discharged on March 15, 1990, without rendering a verdict on the allegations. There was no legal necessity for the *599discharge of the jury, nor did defendant consent to the discharge without verdict at that time. It seems clear that retrial is barred.
The majority do not contend that jeopardy had not attached at the time the jury was sworn on March 7,1990. Rather, they contend that jeopardy did not terminate when the jury was discharged. (Maj. opn, ante, p. 592.) In other words, jeopardy attached when the jury was sworn on March 7, 1990, continued after that jury was discharged without rendering a verdict on the allegations, and continued while another jury was selected, heard the case, and rendered its verdict.
For this novel view the majority draw an analogy to two cases decided by the United States Supreme Court. In one, at arraignment, long before jeopardy attached, defendant offered to plead guilty to a lesser offense and the court accepted the plea over the prosecutor’s objection, and dismissed the remaining counts. The high court determined that there was no double jeopardy bar to trial on the dismissed counts, because defendant had never been subject to trial as to those counts. (Ohio v. Johnson (1984) 467 U.S. 493, 501-502 [81 L.Ed.2d 425, 434-435, 104 S.Ct. 2536].)
The proceeding here is not analogous. Unlike in Ohio v. Johnson, supra, 467 U.S. 493, here jeopardy did attach, a jury was selected and sworn, and defendant was on trial. “The reason for holding that jeopardy attaches when the jury is impaneled and sworn lies in the need to protect the interest of the accused in retaining a chosen jury.” (Crist v. Bretz (1978) 437 U.S. 28, 35 [57 L.Ed.2d 24, 31, 98 S.Ct. 2156].) The defendant in Ohio v. Johnson, supra, 467 U.S. 493, pleaded guilty at the arraignment and so never had a jury to retain, and was never on trial. While the result in that case is not surprising, it offers no guidance in the present case.
The second case the majority offer is Swisher v. Brady (1978) 438 U.S. 204 [57 L.Ed.2d 705, 98 S.Ct. 2699], in which Maryland provided for a two-tier system of trial of juvenile offenses, in which the “accused juvenile is subjected to a single proceeding which begins with a master’s hearing and culminates with an adjudication by a judge.” (Swisher v. Brady, supra, 438 U.S. at p. 215 [57 L.Ed.2d at p. 715].) The court explained that the unitary proceeding did not subject the minor to two trials, nor could the state present additional evidence at the judicial hearing without the minor’s consent. As it is only the judge who acts as final fact finder and adjudicator, the minor is not twice in jeopardy. (Id. at pp. 215-217 [57 L.Ed.2d at pp. 714-716].)
Again, the procedure at issue here is not analogous. We do not have a two-tier system with respect to trial of prior conviction allegations, we have *600a unitary system. There is to be one trial, and we treat the prior conviction allegation as part of the trial on the underlying offenses, to be tried in one single proceeding. As state law does not contemplate a second proceeding before a new jury on the prior conviction allegation, it cannot be said that jeopardy does not terminate until such a second proceeding occurs.
Finally, the majority claim that no interest of defendant’s that is protected by the double jeopardy clause is injured by the proceedings that occurred in this case. (Maj. opn, ante, p. 593.) Not so. One of the three main interests long recognized by the United States Supreme Court as protected by the double jeopardy clause is the interest in having the entire case tried before one tribunal. (United States v. DiFrancesco (1980) 449 U.S. 117, 128 [66 L.Ed.2d 328, 339-340, 101 S.Ct. 426]; Crist v. Bretz, supra, 437 U.S. at p. 35 [57 L.Ed.2d at p. 31]; Arizona v. Washington, supra, 434 U.S. at p. 503 [54 L.Ed.2d at p. 726].) Clearly, this interest was defeated in the present case.
The rule that jeopardy attaches when the jury is sworn or the court as trier of fact begins to hear evidence, is “by no means a mere technicality, nor is it a ‘rigid, mechanical’ rule. It is of course, like most legal rules, an attempt to impart content to an abstraction.” (Serfass v. United States (1975) 420 U.S. 377, 391 [43 L.Ed.2d 265, 276, 95 S.Ct. 1055].) I would adhere to the rule to preserve the content of the double jeopardy clause.
II
I also disagree with the decision that defendant waived any claim of error under Penal Code section 1025 by failing to object to the dismissal of the jury. (Maj. opn., ante, p. 589.)
The majority emphasize that defendant did not object to dismissal of the jury before trial on the remaining allegations. That is a strange requirement to place on the defendant. According to the majority he must, in effect, stand up and say, “Your Honor, I object to your dismissal of the jury because they have not heard all of the remaining charges and evidence against me.”
Penal Code section 1025 makes the allegation of a prior conviction a matter of proof for the prosecutor, like any other charge in the indictment or information. The burden is on the prosecution to establish the valid prior conviction. The majority do not argue otherwise. Penal Code section 1164, subdivision (b), also clearly places on the trial court the obligation to assure itself that the prior conviction allegations have been dealt with before the jury is discharged. The prosecutor and the court, therefore, had the burden of assuring that the jury was not dismissed before trial of the prior conviction allegations.