The defendant, Arthur W. Spaulding, was indicted by a grand jury in January, 1986, on charges of aggravated rape and armed robbery, and he was arraigned on those indictments in March, 1986. When, by June, 1988, he had not yet been tried on the charges, he filed a motion to dismiss them on the ground that he had not been brought to trial within twelve months of his arraignment as required by Mass. R. Crim. P. 36 (b) (1), 378 Mass. 909 (1979), and on[*504] the ground that he was entitled to dismissal for prejudicial delay under Mass. R. Crim. P. 36 (c), 378 Mass. 909 (1979), because the conduct of the prosecuting attorney was unreasonably lacking in diligence. The defendant’s motion was denied, and he was subsequently convicted by a jury. ^[1] On appeal, he claims error in the denial of his motion to dismiss. ^[2] We transferred the case to this court on our own motion, and we now conclude that the defendant’s rule 36 motion should have been allowed.

Under Mass. R. Crim. P. 36, ^[3] a criminal defendant who is not brought to trial within one year of the date of arraignment is presumptively entitled to dismissal of the charges unless the Commonwealth justifies the delay. The delay may be excused by a showing that it falls within one of the “[ejxcluded [pjeriods” provided in rule 36 (b) (2), or by a showing that the defendant acquiesced in, was responsible for, or benefited from the delay. Commonwealth v. Lauria, ante 63, 68 (1991). Commonwealth v. Mattos, 404 Mass.[*505] 672, 674-675 (1989). Barry v. Commonwealth, 390 Mass. 285, 297 (1983). The defendant was arraigned on March 7, 1986; his trial, therefore, should have begun by March 7, 1987. On June 8, 1988, the date when the parties stipulated that the running of time under rule 36 was tolled, ^[4] the Commonwealth was 458 days over the due date and needed to justify that number of excludable days.

In denying the motion to dismiss, the judge ruled that, because the defendant had not objected to any delays in the progress of his case from the time of his arraignment in March, 1986, ^[5] until February 19, 1988 (when he objected to a continuance granted because a witness was unavailable), the entire period preceding the defendant’s first objection to delay was to be excluded from rule 36 calculations. This ruling was erroneous.

It is true that criminal defendants are obligated to object to delays in order to “press their case through the criminal justice system,” Barry v. Commonwealth, supra at 297, and that in many circumstances the failure of a defendant to object to a delay may properly be considered to be acquiescence in. the delay and therefore not chargeable against the Commonwealth. In Commonwealth v. Lauria, supra at 68-69, the defendants were held to have acquiesced in delay by failing to inquire about the status of motions they had filed. In Commonwealth v. Dias, 405 Mass. 131, 139 (1989), and Commonwealth v. Farris, 390 Mass. 300, 305 (1983), the defendants acquiesced in delay by failing to object to continuances granted by the court. In Commonwealth v. Farris, supra at 305-306, and in Barry v. Commonwealth, supra at[*506] 298 n.16, we held that a defendant who does not object when a trial date passes without any action being taken will be deemed to have acquiesced in that delay. However, we have never held that rule 36 time does not begin to run until the defendant first makes an objection. Such a holding would upset the balance of obligations envisioned by the rule, under which the “primary responsibility for setting a date for trial lies with the district attorney.” Barry v. Commonwealth, supra at 296 n.13. Commonwealth v. Wysocki, 28 Mass. App. Ct. 45, 47 (1989). See also G. L. c. 278, § 1 (1990 ed.). ^[6]

In order to decide whether the time limits under rule 36 have run in this case, ^{[7] [8]} it is necessary to consider in more detail the period of time between the defendant’s arraignment and his filing of the motion to dismiss. The record consists of the docket and clerk’s minutes, a statement of agreed facts, and other materials. For purposes of this analysis, the time is divisible into three periods. (An Appendix to the opinion contains a chronological listing.)

1. March 7, 1986, to February 20, 1987. ^[8] Nearly all of this first year following the defendant’s arraignment may be excluded in the computation of rule 36 time. With the exception of the twenty-one days between the arraignment, on March 7, 1986, and a pretrial conference scheduled for March 28, 1986 (a period normally included in the calcula[*507] tion, see Barry v. Commonwealth, supra at 296 n.13), the balance of this period, totalling 329 days, may be excluded because the defendant specifically agreed to continuances, ^{[8] [9]} or had pretrial motions pending, thus excluding the time under Mass. R. Crim. P. 36 (b) (2) (A) (v).

2. February 21, 1987, to February 18, 1988. This period contains some excludable days attributable to the defendant’s acquiescence; however, "most of the time must count toward the rule 36 time limit because of the Commonwealth’s failure to prosecute the case.

On February 20, 1987, ^[10] the court granted a continuance, to which the defendant did not object, and set the case for trial on February 24, 1987; there is no docket entry for that date. The next docket entry, March 4, 1987, shows another continuance by the court to March 9 for trial; there is no docket entry for March 9. The defendant argues that, because the delay during this period was largely the result of court congestion, it should not be excluded from the computation of rule 36 time. While normally court congestion is not a sufficient justification for the denial of the right to a speedy trial, see Commonwealth v. Beckett, 373 Mass. 329, 332-333 (1977), as we held in Commonwealth v. Conefrey, 410 Mass. 1, 5 (1991), “reasons of court congestion may be adequate to excuse delay when ... a defendant has agreed to a continuance based on congestion, rendering him at least partially responsible for the delay.” We think a similar result is justified when a defendant allows a scheduled trial date to pass without objection, and we hold that the defendant acquiesced in this delay. See Barry v. Commonwealth, supra at 298 n.16;[*508] Commonwealth v. Farris, supra at 305-306. The period of his acquiescence lasted from February 25, the day following the scheduled trial date, until April 3, 1987, when the case was transferred for April sitting; at that point, the responsibility for scheduling the case for trial again passed to the Commonwealth.

After the case was transferred for the April sitting, no activity occurred- from April 3, 1987, until October 27, 1987, when, according to the statement of agreed facts, the case was continued to November 2, 1987, for trial at the request of the Commonwealth and without objection by the defendant. ^[11] Because it is the prosecutor who controls the setting of cases for trial, this seven-month period is chargeable to the Commonwealth under rule 36 time limits.

The defendant did not enter an objection when the new date set for trial, November 2, passed; therefore, he may be charged with acquiescence until November 23, on which date the case was continued “for status.” At this point, responsibility for this case again passed to the Commonwealth. There was no activity in this case from November 23, 1987, until February 18, 1988, when a judge ordered the case returned to the first criminal session for a status date. This three-month delay is included in the rule 36 calculations.

During this period, a total- of sixty-nine days may be excluded from the computation of rule 36 limits.

3. February 19, 1988, to June 8, 1988. On February 19, 1988, the court granted a continuance to the Commonwealth because one of the witnesses was unavailable to testify at[*509] trial. The defendant did object to this delay; the continuance, however, was properly granted under rule 36 (b) (2) (B). ^[12] The case was continued to March 28, 1988. According to the statement of agreed facts, on that date, “the case was sent out to a session. Soon after, the district attorney had the case sent to another session because the former session was turned into a ‘homicide session.’ ” By June 8, 1988, when the parties stipulated that the running of rule 36 time was tolled in order for the judge to consider the defendant’s motion to dismiss, the case had not yet been called. Because the defendant objected to the continuance granted because of the witness’s unavailability, we think that the responsibility for bringing the defendant to trial following that continuance should fall on the Commonwealth.

During this period, therefore, thirty-nine days may be excluded from the rule 36 calculations.

In conclusion, after excluding from the computation all the time that rule 36 and the case law contemplate should be the responsibility of the defendant, the Commonwealth has justified 437 days and is still twenty-one days short of the number of days it is required to excuse.

The Commonwealth relies almost exclusively on the rationale of the judge that no delay is chargeable to the Commonwealth until the defendant first objects, and has offered no explanation for the delays in this case other than the defendant’s acquiescence. No argument is made, either in the Commonwealth’s opposition to the defendant’s motion or on appeal, that the defendant benefited by the delay or that the defendant was not ready for trial, see Commonwealth v. Lauria, supra at 67-71. ^[13]

[*510] The circumstances of this case are unlike those in Commonwealth v. Lauria, where, during a delay caused by the pendency of the defendants’ pretrial motions, the prosecutor diligently brought the case to the judge’s attention. In that case, we held that the public interest would “be frustrated by a rigid application of rule 36 where the prosecution has behaved responsibly,” id. at 70. In this case, an assessment of “counsel’s respective degrees of interest and activity in assisting the court to provide a speedy trial,” id. at 70, discloses the Commonwealth’s performance to be wanting in a case which, even granting every indulgence to the Commonwealth, took an extraordinary length of time to bring to trial. The rule requires that the indictments in this case be dismissed.

The judgments of conviction are reversed and the verdicts set aside. The order denying the motion to dismiss the indictments on which the defendant was convicted is vacated, and an order is to enter allowing the motion to dismiss as to those indictments.

So ordered.

Appendix.

Days Days

Time Period Excluded Included

21 days 1. March 8, 1986 - March 28, 1986

Establishment of date for pretrial conference report and motions. Not excludable (see Barry v. Common wealth, supra at 296 n.13).

2. March 29, 1986 - February 4, 1987 313 days

Continuances by agreement and pendency of pretrial motions excludable under rule 36 (b) (2) (A) (v).

3. February 5, 1987 - February 20, 1987 16 days

Continuances by agreement.

[*511] 4. February 21, 1987 - February 24, 1987 4 days

Continuance to which defendant did not object.

5. February 25, 1987 - April 3, 1987 38 days

Defendant acquiesced in delay by allowing trial date to pass without objection (see Barry v. Common wealth, supra at 298 n.16).

6. April 4, 1987 - October 27, 1987 207 days

No activity after case transferred on April 3, for April sitting.

7. October 28, 1987 - November 2, 1987 6 days

Case continued to November 2, for trial at request of Commonwealth and without objection by defendant.

8. November 3, 1987 - November 23, 1987 21 days

Defendant acquiesced in delay by allowing trial date to pass without objection.

9. November 24, 1987 - February 18, 1988 87 days

No activity after case continued to November 23 for status.

10. February 19, 1988 - March 28, 1988 39 days

Continuance granted because of unavailability of witness excludable rule 36 (b) (2) (B).

11. March 29, 1988 - June 7, 1988 71 days

No activity after case sent to new session.

12. June 8, 1988

Parties stipulated that running of time under rule 36 would be tolled for purposes of defendant’s motion to dismiss.

TOTAL

437

386

(21 days under 458 days required to justify)

(21 days over 365-day limit of rule 36)