¶ 1 The United States District Court for the Northern District of Oklahoma certified two first impression questions of Oklahoma law:
1. Under the 2005 version of the Oklahoma Standards for Workplace Drug and Alcohol Testing Act, are evidential breath tests to determine an employee's blood alcohol content, laboratory services which must be confirmed by a licensed testing facility?
2. What is the standard to determine whether an employer has committed a willful violation of the Testing Act as the term in used in 40 O0.$.2001 § 563(A)7
¶ 2 The plaintiff, Dennis E. Estes (Estes), a mechanical engineer, was employed by the defendant, ConocoPhillips Company (Conoco) for over thirty years. On the evening of May 23, 2005, his son came home from college, and Estes and his family celebrated with a family cookout, at which he drank beer and wine. On May 24, 2005, Estes arrived at work around 1:00 pm, and his supervisor asked him to submit to a drug and alcohol test, which, unbeknownst to Estes, had been scheduled several days prior, pursuant to Conoco's testing policy. There is no allegation that Estes appeared intoxicated, that he had ever been intoxicated at work, or that he had been anything but a model employee.
¶ 3 Estes was sent to Conoco's Ponea City Medical Clinic (the clinic), where a registered nurse utilized an "evidential breath testing device"2 (EBT) to test Estes' blood alcohol content (BAC) at 1:80 pm. At the 'time of his test, it had been at least ten hours since Estes' last drink. The initial test results showed that Estes had a BAC of 0.076 gm/dl.3 At least fifteen minutes later, a second EBT indicated that Estes had a BAC of 0.064 The maximum allowable BAC under Conoco's testing policy was 0.04 gm/dl, a level 50% lower than Oklahoma's legal limit for operating a motor vehicle under the influence of alcohol: 0.08 gm/dl.4
*521¶ 4 When a police officer subjects an operator of a motor vehicle to an EBT, Oklahoma law mandates that a sufficient quantity of breath must be obtained and retained for 60 days so that the person may have an independent laboratory conduct a test on the sample preserved.5 However, the Testing Act does not require employers to use an EBT that retains a breath sample for retesting.6 The clinic used the Intoximeter Alco-sensor IV, the least expensive EBT included in the BOH Rules' table of approved EBTs.7 The Intoximeter Alcosensor IV is a handheld device powered by a nine volt battery that is of the "blow through" variety, therefore, no sample of Estes' breath was collected which could be independently tested at a later date, and no sample of any bodily fluid was taken or preserved. Based solely on the EBT results and no other evidence, Conoco terminated Estes within an hour of the administration of the second EBT, and informed him that there was no procedure to appeal his dismissal. It is undisputed that, at the time, the clinic did not have a license to perform laboratory services under the Testing Act.8
¶ 5 On August 4, 2005, Estes filed a wrongful termination suit in the United States District Court for the Northern District of Oklahoma alleging that his employment was terminated in willful violation of the Testing Act. He sought injunctive relief to prevent Conoco from engaging in future testing and declaratory relief to reinstate him to his previous position. He also sought monetary damages including lost wages, compensatory damages for emotional distress and damage to his reputation, as well as attorney's fees, costs, and expenses. On *522August 25, 2005, Conoco moved to dismiss Estes' complaint for failure to state a cause of action under the Testing Act. On November 7, 2006, the federal court certified the questions to this Court.
1.
¶ 6 EVIDENTIAL BREATH TESTS ARE LABORATORY SERVICES WHICH MUST BE CONFIRMED BY A LICENSED TESTING FACILITY BEFORE AN EMPLOYER MAY TAKE DISCIPLINARY ACTION IN RELIANCE ON THOSE TEST RESULTS.
¶ 7 The Oklahoma Standards for Workplace Drug and Aleohol Testing Act (the Testing Act/the Act), 40 0.8. §§ 551-565, was enacted in 1998 to govern employers who test job applicants or employees for drugs or alcohol.9 The Testing Act enabled the Oklahoma State Board of Health (Board of Health) to promulgate rules for the licensure and regulation of testing facilities, and for the establishment of minimum testing standards and procedures.10 In 1994, the Board of Health enacted the Drug and Alcohol Testing Rules (BOH Rules), OAC 310:638.
¶ 8 The Testing Act sets out the requirements for licensure at 40 0.9.2001 § 558. It provides that no testing facility may provide laboratory services to an employer to test for the presence or absence of drugs or alcohol unless it meets the qualifications for testing facilities set by the Testing Act and the BOH Rules.11 The Act defines the term "testing facility" as any clinic or facility which provides laboratory services to test for the presence of drugs or alcohol.12 The term labora*523tory services is not defined either in the Testing Act or the BOH Rules. It is undisputed that the clinic was not licensed under the Testing Act at the time it administered the EBT, and Estes contends that because of this, Conoco was not entitled to terminate him based on the results of the EBT confirmation test performed at the clinic. Conoco counters that EBT are not laboratory services as contemplated by the Testing Act, and therefore do not require licensure.
¶ 9 The Testing Act requires that two tests be performed when an employer uses an EBT to test employees for alcohol, the first is called a sereening test and the second is called a confirmation test.13 The BOH Rules repeatedly address confirmation tests for alcohol conducted using an EBT. BOH Rule 310:638-1-4(b)(2) provides, "Confirmation tests. Breath or blood shall be used for the confirmation test for alcohol." Rule 810:638-7-5 provides in pertinent part: "All positive initial alcohol screening tests shall be confirmed using breath analyzed by an EBT or blood analyzed by gas chromatography.14 Furthermore, alcohol confirmation tests conducted using an EBT are heavily regulated by BOH rules. BOH Rule 310:638-7-6 is entitled "Breath Alcohol Confirmation Tests," and contains two and a half pages of detailed regulations for conducting alcohol confirmation tests using an EBT.15 Throughout this rule, the acronym "EBT" is used forty-four times. In depositions, both Board of Health General Counsel Gary Gardenhire and Board of Health Director of Facility Services Dean Bay testified that the Board of Health has historically considered EBT to be a laboratory service requiring Heensure.16
Pursuant to the Administrative Procedures Act, 75 0.98.2001 §§ 250-328, the Legislature may delegate rulemaking authority to agencies, boards, and commissions to facilitate the administration of legislative policy.17 Administrative rules are valid expressions of lawmaking powers having the force and effect of law.18 Administrative rules, *524like statutes, are to be given a sensible construction.19
¶ 11 Statutory construction by agencies charged with the law's enforcement is given persuasive effect especially when it is made shortly after the statute's enactment.20 Nevertheless, if the Legislature disagrees with an agency interpretation, it may: 1) delay, suspend, veto, or amend any rule or proposed rule by joint resolution; 2) disapprove a permanent or emergency rule at any time if it determines the rule to be inconsistent with legislative intent; or 3) make emer-geney rules ineffective through its disapproval.21 None of these actions have been taken by the Legislature in regard to the BOH rules. The Legislature's silence is evidence of the lawmakers' consent and adoption of the administrative construction.22
¶ 12 This Court will show great deference to an agency's interpretation of its own rules.23 When the terms of a regulation are amenable to more than one meaning, we ordinarily defer to the interpretation adopted by those charged with the duty of administration.24 When choosing between two or more possible meanings of a regulation, controlling weight may be given to long-continued administrative usage unless it is plainly erroneous or inconsistent with the language.25 Deference to an agency's interpretation is even more clearly in order when the construction is that of an administrative regulation rather than a statute.26
¶ 13 It is clear that the Board of Health has interpreted alcohol confirmation tests utilizing EBT as laboratory services requiring licensure, and that the Legislature has adopted this construction. Therefore, we find that under the version of the Testing Act in effect on May 24, 2005, evidential breath tests to determine an employee's blood alcohol level are laboratory services which must be confirmed by a licensed testing facility before an employer may take disciplinary action in reliance on those test results.
H.
¶ 14 THE TERM WILLFUL VIOLATION AS FOUND IN 40 0.8.2001 § 563(A) *525MEANS CONSCIOUS, PURPOSEFUL VIOLATIONS OF THE TESTING ACT OR DELIBERATE DISREGARD OF THE TESTING ACT BY THOSE WHO KNOW OR SHOULD HAVE KNOWN OF ITS PROVISIONS.
¶ 15 Neither the Testing Act nor the BOH Rules define the term willful. Conoco argues that the term means that a violator had some knowledge or understanding that it is committing an act prohibited by the Testing Act. Estes argues that the term means that a violator knew or should have known its actions were in violation of the Testing Act. Title 40 0.$.2001 $ 568(A) provides:
Any person aggrieved by a willful violation of the Standards for Workplace Drug and Alcohol Testing Act may institute a civil action in a court of competent jurisdiction within two (2) years of the person's discovery of the alleged willful violation or of the exhaustion of any internal administrative remedies available to the person, or be barred from obtaining the relief provided for in subsection B of this section. [Emphasis added.]
¶ 16 The primary goal of statutory interpretation is to ascertain and follow the intent of the Legislature.27 Where a statute's meaning is ambiguous or unclear, we employ rules of statutory construction to give the statute a reasonable construction that will avoid absurd consequences.28 It is important in construing the Legislative intent behind a word to consider the whole act in light of its general purpose and objective, considering relevant portions together to give full force and effect to each.29 A statute will be given a construction, if possible, which renders every word operative, rather than one which makes some words idle and meaningless.30 We presume that the Legislature expressed its intent and intended what it expressed, and statutes are interpreted to attain that purpose and end, championing the broad public policy purposes underlying them.31
¶ 17 The term willful does not have a uniform meaning throughout our statutes. As the Court stated in Wick v. Gunn, 1917 OK 607, ¶ 3, 169 P. 1087, there are "numerous definitions of the word [willful] by both lexicographers and jurists." In the context of a willful violation of the Alcoholic Beverage Control Act, this Court held: "The word 'willfully' is of similar import or the equivalent of 'knowingly' [and] requires that the licensee at least have some knowledge of the commission of the prohibited acts.32 The Court held that a willful violation of the Open Meetings Act, "does not require a showing of bad faith, malice, or wantonness, but rather, encompasses both conscious, purposeful violations of the law and blatant or deliberate disregard of the law by those who know, or should know, the requirements of the [Open Meetings] Act.33
¶ 18 When used to determine whether a Workers' Compensation claimant willfully fails to use safety equipment, this Court held that the term signifies "more than a mere act of the will, and carries with it the idea of premeditation, obstinacy, and intentional *526wrongdoing."34 Willful neglect of a teacher's dutics is defined as "a knowingly and purposeful violation of a teacher's duties."35 Construing willful maladministration by a public officer, the Court held:
Every voluntary act of a human being is intentional; but, generally speaking, a voluntary act becomes willful in law only when it involves some degree of conscious wrong or evil purpose upon the part of the actor, or at least an inexcusable carelessness on his part, whether the act be right or wrong.36
Because the term willful does not have a singular meaning, it must be construed within the confines of the Act in which it appears.
¶ 19 This Court has addressed the Testing Act in only one prior case: McClure v. ConocoPhillips Co., 2006 OK 42, 142 P.3d 390. As here, we answered a certified question from the United States District Court for the Northern District of Oklahoma. There, we answered that an employer did not violate the Testing Act by using the same EBT to perform a screening test and a confirmation test. Because we did not find a violation of the Testing Act in McClure, we did not reach the question of what constituted a willful violation of the Testing Act.
¶ 20 Because the term willful is undefined by the Testing Act and the BOH Rules, we must determine the legislative intent behind the term by looking to the general purpose and objective of the Testing Act. The Testing Act states that it is not intended to require or encourage employers to conduct drug or alcohol testing of employees, but that employers who do choose to conduct such tests are to be governed by both the Testing Act and the BOH Rules.37 The purpose behind the Testing Act is to create standards for employer drug and aleohol testing so both employees and employers can be assured of due process. Were we to adopt the standard for willful violations urged by Conoco, we would remove any possibility of a civil remedy for an employee in all but the most extreme violations. If an employer could establish ignorance of the Testing Act, the employee would be left without a remedy, thus largely thwarting the Legislature's intent to regulate workplace drug and alcohol testing.
¶ 21 Additionally, the meaning of the term willful as found in the Testing Act may be understood by comparing the civil remedies laid out in § 568(A), with the eriminal penalties contained at 40 0.9.2001 § 565, which provides:
Any person who willfully and knowingly violates the provisions of the Standards for Workplace Drug and Alcohol Testing Act shall be guilty of a misdemeanor and, upon conviction, punishable by a fine of not less than One Hundred Dollars ($100.00) nor more than Five Thousand Dollars ($5,000.00) or imprisonment in the county jail for not more than one (1) year, or by both such fine and imprisonment. [Emphasis added.]
If we were to treat the term willful as synonymous with the term knowing, we would thereby render either § 563 or § 565 meaningless, by construing the standards for obtaining civil and eriminal remedies identical-Ty. This sort of interpretation would work an absurdity, at odds with the purpose of the Testing Act.
¶ 22 It is axiomatic, that in most instances, ignorance of the law is no excuse, and every person is presumed to know the law.38 Therefore, we find that the term will*527ful violation as found in 40 0.8.2001 § 563(A) contemplates not only conscious, purposeful violations of the Testing Act, but also deliberate disregard of the law by those who know, or should have known, of the requirements of the Testing Act.
CONCLUSION
¶ 23 Drug and alcohol testing is not only addressed by the Testing Act and BOH Rules, but also by extensive statutes and administrative rules governing drug and aleo-hol testing performed or directed by law enforcement officers.39 The Rules for the Board of Tests for Drug and Alcohol Influence contain detailed requirements for EBT, the purpose of which are to provide:
. scientific and procedural safeguards to assure the validity and reliability of such tests, designate methods and procedures for breath-aleohol analysis approved by the Board, and prescribe and control other aspects of such tests.40
The Legislature has so extensively regulated EBT and other methods of drug and alcohol testing precisely because the outcomes of these tests carry such weighty consequences, from serious criminal penalties to the often just as serious consequence of termination of employment.41 Given the high stakes, it is clear that the Legislature seeks to control and regulate drug and aleohol testing, whether by law enforcement officials or employers. The means by which the state may determine whether an employer is adhering to the Testing Act and the BOH Rules is the ongoing requirement of licensure. Were we to adopt Conoco's interpretation, employers would need a license to test employees' blood, saliva, hair, or urine for drugs or alcohol, but would not need a license to test breath, thus preventing the State from regulating perhaps the most common method employed to test for alcohol. Such an interpretation would frustrate the purpose of the Testing Act-ensuring due process in workplace drug and alcohol testing by regulating the practice.
¶ 24 One remedy created by the Testing Act is civil liability for employers who have subjected an employee to an adverse employment decision based on a violation of the Testing Act or BOH Rules. The standard for willful violations of the Testing Act includes purposeful violations as well as violations done in deliberate disregard of the Act by those who knew, or should have known, of its provisions. To adopt any other construction would be to transform both the Testing Act and the BOH Rules into no more than detailed suggestions for workplace drug and alcohol testing that employers could make powerless by simply disregarding them.
¶ 25 The crux of the matter is that evidential breath tests are laboratory services which must be confirmed by a licensed testing facility before an employer may take disciplinary action against an employee. The term willful violation means conscious, purposeful violations or deliberate disregard of the Testing Act by those who know or should have known of its provisions.
QUESTIONS ANSWERED.
EDMONDSON, V.C.J., HARGRAVES, OPALA, KAUGER, WATT, TAYLOR, COLBERT, and REIF, JJ., concur.
WINCHESTER, C.J., not participating.