*534OPINION
By the Court,
Shearing, J.:The Nevada Constitution requires the Legislature to adjourn its regular session “not later than midnight Pacific standard time 120 calendar days following its commencement,” and deems any action taken after the deadline void unless it is taken during a special session. The Nevada Legislature commenced its 71st session on Monday, February 5, 2001, and took its final action on Assembly Bills No. 94 and No. 661 on Tuesday, June 5, 2001, between midnight and 1:00 a.m. Pacific daylight saving time. The question presented by these writ petitions is whether the legislative action was constitutional. We conclude that it was, because midnight Pacific standard time (PST) is equivalent to 1:00 a.m. Pacific daylight saving time (PDST); thus, the Legislature’s final action on the bills was taken before the constitutional deadline and the bills must be enrolled and delivered to the Governor.
FACTS
Docket No. 38039
Assembly Bill No. 661 was introduced and read for the first time in the Assembly on March 26, amended on May 22, and passed as amended on May 23, 2001. A.B. 661 was then introduced and read for the first time in the Senate on May 24, amended on May 30 and again on June 4, and finally passed as amended at 11:57:50 p.m. PDST on June 4, 2001 (10:57:50 p.m. *535(PST)). A.B. 661 was returned to the Assembly, which concurred with the Senate’s three amendments to A.B. 661 at 12:24:17 a.m., 12:25:15 a.m. and 12:25:47 a.m. PDST on June 5, 2001 (11:24:17 p.m., 11:25:15 p.m. and 11:25:47 p.m. PST on June 4, 2001).
Thereafter, Brenda Erdoes of the Legislative Counsel Bureau declined to enroll A.B. 661 and did not deliver the bill to the Governor for his action.
On June 15, 2001, the Nevada Mining Association, several mining companies, the Nevada Resort Association, a casino resort, several power and telephone companies, and Senator Dean Rhoads filed an original petition for a writ of mandamus (docketed as No. 38039) to compel Legislative Counsel to fulfill her constitutional and statutory duties to enroll A.B. 661 and deliver the bill to the Governor for his action.
Docket No. 38053
Assembly Bill No. 94 was introduced and read for the first time in the Assembly on February 12, amended on April 20, and passed as amended on May 23, 2001. A.B. 94 was then introduced and read for the first time in the Senate on April 24, amended on May 28, and passed as amended on May 28, 2001. A.B. 94 was returned to the Assembly, which did not concur with the Senate’s amendments. The Senate did not recede from its amendments, so each chamber appointed the First Conference Committee on A.B. 94. On June 4, 2001, the Committee reported back to the Assembly with the recommendation to concur with the Senate’s amendments of A.B. 94 and to further amend the bill. The Assembly adopted the First Conference Committee Report for A.B. 94, and the Report was sent to the Senate. The Senate adopted the Report at 12:38:59 a.m. PDST on June 5, 2001 (11:38:59 p.m. PST on June 4, 2001).
Thereafter, Brenda Erdoes of the Legislative Counsel Bureau declined to enroll A.B. 94 and did not deliver the bill to the Governor for his action.
On June 20, 2001, the Nevada Association of Counties and the Nevada Association of County Clerks and County Election Officials filed an original petition for a writ of mandamus (docketed as No. 38053) to compel Legislative Counsel to fulfill her constitutional and statutory duties to enroll A.B. 94 and deliver the bill to the Governor for his action.
PROPRIETY OF WRIT RELIEF
A writ of mandamus is available to compel a public officer to perform an act that the law requires as a duty resulting from an *536office, trust or station.1 A writ of mandamus will not issue, however, to compel a public officer to perform an act that the officer has no legal duty or authority to perform.2 A writ of mandamus also will not issue if the petitioner has a plain, speedy, and adequate remedy at law.3 Petitions for extraordinary relief are addressed to the sound discretion of this court.4
Here, petitioners do not have a plain, speedy and adequate remedy at law. Moreover, these writ petitions raise an issue of first impression, one that needs clarification and is a matter of public importance: What, precisely, is the constitutional deadline for adjournment, before which a bill that has passed both houses must be enrolled and delivered to the Governor for action and after which any legislative action is void? We conclude that our consideration of these writ petitions is warranted.5
LEGISLATIVE PROCESS
Under Nevada’s Constitution, “a majority of all the members elected to each house is necessary to pass every bill or joint resolution,” and “an affirmative vote of not fewer than two-thirds of the members elected to each house is necessary to pass a bill or joint resolution which creates, generates, or increases any public revenue in any form.”6 For a bicameral legislature such as Nevada’s to pass a bill, both houses of the legislature must concur in and pass the same version of the bill during the same legislative session.7 Thus, if each house passes a different version of a bill, both houses must subsequently concur in and pass the same *537version of the bill before they adjourn the legislative session.8 If each house passes a different version of a bill and both houses do not subsequently concur in the same version, the bill has not passed the legislature, and no provision of the bill can become law.9
Under NRS 218.340, “[w]hen any bill or resolution is passed by both houses, the secretary of the senate or the chief clerk of the assembly shall immediately transmit the same to the legislative counsel to be enrolled.” NRS 218.380 provides that “[a]n enrolled bill must be delivered by the legislative counsel, or such person as he designates in writing, to the governor for his action.” In carrying out the statutory duties set forth in NRS 218.340 and NRS 218.380, Legislative Counsel is complying with the constitutional mandate that “[ejvery bill which may have passed the Legislature, shall, before it becomes a law be presented to the Governor.”10 Consequently, if A.B. 94 and A.B. 661 were passed before the constitutional adjournment deadline, Legislative Counsel has a duty to enroll them and deliver them to the Governor. We conclude that the bills were passed, and that they therefore must be enrolled and delivered.
DURATION OF THE REGULAR SESSION
The sessions of the Nevada Legislature are biennial and, under the Nevada Constitution, must commence on “the 1st Monday of February following the election of members of the Assembly, unless the Governor of the State shall, in the interim, convene the Legislature by proclamation.”11 The time for adjournment is constitutionally mandated under article 4, section 2, subsection 2, which provides:
The Legislature shall adjourn sine die each regular session not later than midnight Pacific standard time 120 calendar days following its commencement. Any legislative action taken after midnight Pacific standard time on the 120th cal*538endar day is void, unless the legislative action is conducted during a special session convened by the Governor.
Although this provision seems plain on its face, petitioners and Legislative Counsel advocate different interpretations of two essential parts: “120 calendar days following its commencement” and “midnight Pacific standard time.”12 We must therefore decide whether the first day of the regular legislative session is included in the 120-day durational limit and whether midnight Pacific standard time is the same as midnight Pacific daylight saving time.
CONSTITUTIONAL CONSTRUCTION
When construing constitutional provisions, we use the same rules of construction used to interpret statutes.13 Our primary task, then, is to ascertain the intent of those who enacted the durational limit on legislative sessions, and to adopt an interpretation that best captures their objective.14 We must give words their plain meaning unless doing so would violate the spirit of the provision.15 We are concerned here with a narrow legal issue, not with the legislation itself; we express no opinion on the merits of A.B. 94 or A.B. 661.
DISCUSSION
We first consider the meaning of the phrase ‘ ‘ 120 calendar days following its commencement.” Petitioners urge us to apply the common law rule, which is reflected in Nevada’s rules of court procedure,16 that the day of the act or event from which the designated period begins to run should not be included. Under this interpretation, which would in effect create a 121-day durational limit, June 5, 2001, would have been the last day of the 71st regular legislative session.17
*539Although the argument is a reasonable one and is consistent with common practice,18 we reject it because the intent of the provision’s framers and the voters who ratified it is clear. This constitutional amendment was proposed and passed by the 1995 Legislature, agreed to and passed by the 1997 Legislature, and approved and ratified by the citizens of Nevada at the 1998 general election. The ballot question submitted to the voters at the general election read (emphasis ours):
Shall the Nevada Constitution be amended to limit the length of Nevada’s regular legislative sessions to not more than 120 calendar days and require the Governor to submit the proposed executive budget to the Legislature at least 14 days before the start of each regular session?
The explanation that accompanied the ballot question also specified that the amendment “would limit future regular sessions to not more than 120 calendar days, starting in the 1999 session.” This clear statement of intent dissolves any ambiguity inherent in the phrase “120 calendar days following its commencement.” The day of commencement is included, and the adjournment deadline for the 71st regular legislative session was “midnight Pacific standard time” on the 120th calendar day: June 4, 2001.
But precisely when was “midnight Pacific standard time?” Nevada’s change from Pacific standard time to Pacific daylight saving time on the first Sunday of April, midway through the regular session, created an ambiguity in the deadline. Is midnight Pacific standard time the same as midnight Pacific daylight saving time? We conclude that it is not and cannot be the same.
First, the terms “Pacific standard time” and “Pacific daylight saving time” are clear and distinct, with commonly understood meanings. Pacific daylight saving time denotes a time one hour later than Pacific standard time, and results from advancing the clock one hour every April, from 2:00 a.m. to 3:00 a.m. When the constitutional amendment was drafted, the Legislature obviously knew that the adjournment deadline would come sometime in early June after Nevada had changed over to Pacific daylight saving time. But instead of specifying that the regular session must end at “midnight Pacific daylight saving time,” or just *540“midnight,” the Legislature presented to the voters and the voters approved “midnight Pacific standard time” as the end of the session. We should give effect to this purposeful choice, rather than try to redefine “midnight Pacific standard time” as “midnight Pacific daylight saving time.” In choosing this interpretation, the Legislature acted on Legislative Counsel’s opinion that this is a reasonable construction of the provision. We agree that it is, and the Legislature is entitled to deference in its counseled selection of this interpretation.
Second, the historical development of these terms supports the conclusion that they are not interchangeable. During the 1880s, railroad companies divided the United States into four standard time zones to regulate train schedules and to avoid the uncertainties caused by the use of solar time.19 In 1918, the United States Congress established “standard time” as the law of the nation.20 The territory of the United States was divided into five zones, and a standard time for each zone was fixed based on the mean astronomical or solar time of a specified degree of longitude west from Greenwich.21
The Act of 1918 also established daylight saving time, but that provision was repealed in 1919. Daylight saving time was reestablished by Congress during World War II, but after the war its use varied among state and local governments.22 In 1966, Congress enacted the Uniform Time Act, which standardized the dates on which daylight saving time begins and ends, but allowed states to exempt all or portions of their territories from its observance.23 Congress enacted earlier starting dates for daylight saving time in 1974 and 1975, “energy crisis” years, but amended the Act in 1986 so that daylight saving time always begins on the first Sunday in April and ends on the last Sunday in October.
A simple illustration demonstrates why midnight Pacific standard time is not the same as midnight Pacific daylight saving time. Nevada lies within the fifth time zone, which is designated and known as Pacific standard time.24 Utah and Arizona, which border Nevada, lie within the fourth time zone, which is designated *541and known as mountain standard time. Arizona has exempted itself from daylight saving time,25 but Nevada and Utah have not. Consequently, when Nevada and Utah advance their clocks on the first Sunday in April, and change from Pacific standard time to Pacific daylight saving time and from mountain standard time to mountain daylight saving time, respectively, Arizona remains on mountain standard time. Arizona does not change times, but its clocks become synchronized with Nevada’s clocks instead of Utah’s. Since Nevada’s Pacific daylight saving time is the same as Arizona’s mountain standard time, it is not and cannot be the same as Pacific standard time as well.
Similarly, had Nevada exempted itself from daylight saving time, or should it choose to do so in the future, Nevada would remain on standard time when its fifth time zone neighbors change to daylight saving time. After the change, Nevada and California would both still be on Pacific time, but Nevada would be on Pacific standard time and California would be on Pacific daylight saving time. As a result, their clocks would not strike midnight simultaneously; at midnight in Nevada it would be 1:00 a.m. in California. Clearly, Pacific standard time is not the same as Pacific daylight saving time.
The standard time zones do not change, and standard time also does not change. Although daylight saving time may become the “standard” for nearly seven months out of the year for those states in the Pacific zone that choose to use it, it does not become “Pacific standard time.” That term is precise and specific. Pacific standard time is, by design and definition,26 one hour earlier than Pacific daylight saving time. We are not free to presume that the framers of the durational limit and those who enacted it meant anything other than exactly what they said.27
Third, article 4, section 2, subsection 2 gives the Legislature 120 days for its regular session. A day consists of 24 hours, so the Legislature has 2,880 hours before it must adjourn under the constitutional deadline. When Nevada advanced its clocks on the first Sunday in April, that day was shortened to 23 hours. Although the Legislature may choose not to use every hour allotted to it — it does not, for instance, convene at 12:01 a.m. *542although it could — its last available hour expired not at midnight Pacific daylight saving time on June 4, 2001, but instead one hour later.28
CONCLUSION
The fundamental intent of the constitutional amendment is to set a durational limit on legislative sessions. Our construction of the provision gives full effect to the 120-day limitation, without extending the limitation beyond its terms or frustrating its purpose. It would be absurd for us to interpret Pacific standard time to be the same as Pacific daylight saving time, and we decline to do so.29 Midnight Pacific standard time on June 4, 2001, was the equivalent of 1:00 a.m. Pacific daylight saving time on June 5, 2001, and the Legislature had authority to act until the clock struck 1:00 a.m. Since A.B. 94 and A.B. 661 were passed by both houses before the adjournment deadline, Legislative Counsel has a constitutional and statutory duty to enroll the bills and deliver them to the Governor.
Accordingly, we grant these petitions. The clerk of this court shall issue writs of mandamus compelling Legislative Counsel to enroll Assembly Bills No. 94 and No. 661, and deliver them to the Governor for action.
Young, Rose and Becker, JJ., concur.NRS 34.160; see Brewery Arts Ctr. v. State Bd. Examiners, 108 Nev. 1050, 1053, 843 P.2d 369, 372 (1992).
Conklin ex rel. v. Buckingham, 58 Nev. 450, 453-54, 83 P.2d 462, 463 (1938).
NRS 34.170.
Smith v. District Court, 107 Nev. 674, 818 P.2d 849 (1991).
Business Computer Rentals v. State Treas., 114 Nev. 63, 67, 953 P.2d 13, 15 (1998) (noting that when “an important issue of law needs clarification and public policy is served by this court’s invocation of its original jurisdiction, . . . consideration of a petition for extraordinary relief may be justified”).
Nev. Const, art. 4, § 18(1) & (2).
McDougal v. Davis, 143 S.W.2d 571, 571 (Ark. 1940) (observing, as an elementary proposition, that “[i]t is essential, of course, to the enactment of a bill into a law that both the House and the Senate shall concur in and pass the same bill”); accord Lee v. City of Decatur, 172 So. 284, 285 (Ala. 1937); Watts v. Town of Homer, 207 So. 2d 844, 846 (La. Ct. App. 1968); Opinion of the Justices, 83 A.2d 738, 741 (N.H. 1950).
See Conway v. Searles, 954 F. Supp. 756, 768 (D. Vt. 1997); PA AFL-CIO ex rel. George v. Com., 757 A.2d 917, 921-23 (Pa. 2000); League of Women Voters v. Com., 683 A.2d 685, 688 (Pa. Commw. Ct. 1996).
See McDougal, 143 S.W.2d at 571; Moore v. Neece, 114 N.W. 767, 768-69 (Neb. 1908); see also State ex rel. Grendell v. Davidson, 716 N.E.2d 704, 709 (Ohio 1999) (noting that “Relators’ contention that when the House and Senate pass different versions of a bill, the nondiffering provisions contained in the differing versions become law, is consequently meritless”).
Nev. Const, art. 4, § 35.
Nev. Const, art. 4, § 2.
We note that near midnight, the Legislature asked Legislative Counsel whether it could reasonably interpret midnight Pacific standard time to mean one hour later than midnight Pacific daylight saving time, so that it could work an additional hour. Legislative Counsel replied that it could, but cautioned the Legislature against doing so. In response to these petitions, Legislative Counsel argues that midnight Pacific standard time should be interpreted to mean the time on the clock.
Rogers v. Heller, 117 Nev. 169, 176 n.17, 18 P.3d 1034, 1038 n.17 (2001).
McKay v. Bd. of Supervisors, 102 Nev. 644, 648, 730 P.2d 438, 441 (1986); State v. Glenn, 18 Nev. 34, 42, 1 P. 186, 189 (1883).
McKay, 102 Nev at 648, 730 P.2d at 442.
See, e.g., NRAP 26(a); NRCP 6(a).
See Alaska Christian Bible Inst. v. State, 772 P.2d 1079, 1080-81 (Alaska 1989) (applying the prevailing common law rule and concluding that Alaska’s *539120-day limit resulted in a 121-day session because the day the legislature convenes is not counted).
See, e.g., Nyberg v. Nevada Indus. Comm’n, 100 Nev. 322, 323-25, 683 P.2d 3, 5 (1984); Rogers v. State, 85 Nev. 361, 364, 455 P.2d 172, 173-74 (1969); Alaska Christian Bible Inst., 772 P.2d at 1081.
McFarlane v. Whitney, 134 S.W.2d 1047, 1051 (Tex. Comm’n App. 1940); State v. Badolati, 6 N.W.2d 220 (Wis. 1942).
McFarlane, 134 S.W.2d at 1051; see also 15 U.S.C. §§ 260-67 (West 1997 & Supp. 2001).
McFarlane, 134 S.W.2d at 1051.
See Annotation, Standard or System of Time, 143 A.L.R. 1238 (1943).
See 15 U.S.C. §§ 260-267.
There are now nine standard time zones, from east to west: Atlantic standard time, eastern standard time, central standard time, mountain standard time, Pacific standard time, Alaska standard time, Hawaii-Aleutian standard time, Samoa standard time and Chamorro standard time. 15 U.S.C. § 263.
The Navajo Indian Reservation in Arizona has not exempted itself; the Navajo Nation, which extends into Arizona, Utah and New Mexico, observes daylight saving time.
Webster’s Tenth Collegiate Dictionary 294 (10th ed. 1997) (“daylight saving time” defined as “time [usually] one hour ahead of standard time”).
See Galloway v. Truesdell, 83 Nev. 13 , 26, 422 P.2d 237, 246 (1967) (noting that when the Legislature chooses one option and not another, it is presumed that the Legislature did so purposely).
See Ellard v. Goodall, 83 So. 568, 569 (Ala. 1919) (holding that a bill of exceptions presented 45 minutes before the expiration of the 90th day if measured by central standard time, but 15 minutes late if measured by daylight saving time, was timely because a state statute allowed 90 days of 24 hours each within which to present a bill of exceptions).
See Rogers, 117 Nev. at 176 n.17, 18 P.3d at 1038 n.17; General Motors v. Jackson, 111 Nev. 1026, 1029, 900 P.2d 345, 348 (1995) (noting that statutory interpretation should avoid absurd or unreasonable results).