The defendant was convicted, after a trial to a jury, of operating under the influence of intoxicating liquor in violation of General Statutes (Rev. to 1985) § 14-227a (a).1 The defendant submitted a request *217to charge the jury on the offense of operating while impaired, General Statutes (Rev. to 1985) § 14-227a (b),2 as a lesser included offense of § 14-227a (a). The defendant now appeals from the trial court’s denial of his request.
The state offered evidence from which the jury might reasonably have found the facts as follows. On June 21, 1985, members of the Connecticut state police were running a spot check for drunk drivers on the eastbound lane of Interstate Route 95 at the West Haven toll plaza. At about 11 p.m., the defendant drove up in the exact change lane behind another car. A trooper was in each lane and talked to each operator as the operator paid the toll. Trooper Peterson saw the defendant feel around for the money for the toll, and he smelled a very strong odor of alcohol. He had not noticed the defendant’s manner of operation because he was watching the cars as they entered the lane and there was a car ahead of the defendant’s car. Peterson told the defendant of the spot check and turned back to make sure oncoming traffic stopped while he had the defendant drive off the highway to a parking area. Peterson asked the defendant to get out of his car, and noticed *218that the defendant held onto the door as he got out. The defendant was laughing and giggling and when he spoke his speech was slurred as if his tongue was heavy.. His choice of words was very confused. His walk was very unstable, his eyes were very glassy and bloodshot and his face was flushed. He fumbled while getting out his license and registration. The defendant agreed to take a number of field sobriety tests. The first test was a balance test in which Peterson asked the defendant to stand straight with his hands at his side and to lift one foot six inches and hold it there for about thirty seconds. The defendant performed the test with each foot, but was unable to hold either foot up more than a few seconds. Peterson administered a walking test which consists of walking a straight line placing one foot in front of the other heel to toe. He had the defendant try to take eight steps forward, turn around and take seven steps back. The defendant was unable to touch heel to toe and could not perform that test. Peterson then had the defendant tilt his head backward, close his eyes, point the index finger straight ahead and then touch his nose. The defendant was unable to point forward and missed his nose with both hands. Peterson then asked the defendant if he knew the alphabet and the defendant said that he did. The defendant said that he understood English, but when asked he was unable to start reciting the alphabet in English. Peterson then asked the defendant to recite the alphabet in Spanish, but the defendant was unable even to start it. Peterson noticed a strong odor of alcohol during the tests and he concluded that the defendant had failed to pass any of the sobriety tests. He concluded that the defendant was intoxicated and he placed him under arrest. Peterson then read the defendant his constitutional rights.3 The defendant said *219that he understood his rights and that he did not want to consult a lawyer and that he understood that his answers to questions would be used against him. He said that he had been drinking and that he had consumed six beers and a half-pint of rum in his car and had nothing to eat between New York City and the West Haven toll. Peterson saw several empty beer cans on the floor of the car and an empty rum bottle in a paper bag on the front seat. The defendant did not know the time or what town he was in.
The defendant testified that he could recite the alphabet in English from the letter “a” through the letter “f” and that he could do the same in Spanish. He said that on June 21, 1985, he worked for eight hours until 4:30 p.m. in West Haven. He drove to Wallingford to pick up his girlfriend and had a drink of Bacardi and an egg sandwich at her house. He left Wallingford with his girlfriend at about 5:30 or 5:45 p.m. to drive her to New York City. He stopped in West Haven and in Greenwich and had a drink of Bacardi in each place. He stopped “somewhere else” and bought a half-pint of Bacardi and two beers. When they arrived at their destination in New York, he did not want to go in, so he had one more shot of Bacardi and one beer. His girlfriend had the other beer and he gave her the bottle of rum because he did not want to have it in the car. After he left his girlfriend, he started back to Connecticut at about 8:30 p.m. He made one stop to buy a hamburger which he ate in the car. There were no beer cans or bottles in the car and he did not have a half-pint Bacardi bottle or any empty bottles in his car. He did not go to the exact change lane at the West Haven toll booth, and when he stopped the woman collecting the toll asked him if he could drive and told him to stay there. She told him not to move his car, and then Peterson came over and told him to drive to the parking lot. He got out of the car and he had his *220license, registration and insurance card all ready. Peterson told him to say the alphabet and he told Peterson that he just knew a couple of letters and he recited it from “a” through “f.” The defendant further testified that he did not tell Peterson anything at all about how - much he had been drinking and the alcohol he had consumed did not affect his driving in any way. He was able to walk without assistance, did not stumble or sway on his feet and did not feel that he had to hold onto the car to stand up. He explained that he could not get his legs straight after an hour and a half sitting down and his legs felt tired.
The defendant also called his sister to testify. She said that her brother had telephoned her on June 21, 1985, at about 11 or 11:30 p.m. and asked her to pick him up because he had been arrested. His speech was normal and clear. She drove to the West Haven toll area, arriving there around 12 or 12:30. Her brother was waiting in the parking lot, and he was laughing and smiling. He did not seem to her to be under the influence of alcohol and his speech was not slurred. She saw no problem with the way he walked. To her, he seemed only to be tired. She also testified that she did not know what “under the influence” meant and that she had not really paid attention to how her brother was walking.
The defendant argues, in brief, that driving while under the influence is to drive while one is impaired “to an appreciable degree.” 3 D. Wright, Connecticut Jury Instructions (2d Ed.) § 930, p. 1558. He argues that, since one cannot be under the influence without being impaired, impairment is a lesser included offense of operating while under the influence. Thus, the trial court erred in refusing to instruct the jury as the defendant requested. The sole issue before us is whether driving while impaired; General Statutes (Rev. to 1985) § 14-227a (b); is a lesser included offense of *221driving while under the influence. General Statutes § 14-227a (a). A criminal defendant is entitled to a lesser included offense instruction in those circumstances where “it is not possible to commit the greater offense . . . without having first committed the lesser; [and] there is some evidence . . . which justifies conviction of the lesser offense . . . .” State v. Whistnant, 179 Conn. 576, 588, 427 A.2d 414 (1980). We, therefore, must determine if it is possible to commit the crime of operating a motor vehicle while “under the influence” without necessarily operating while “impaired,” and whether there was evidence presented sufficient to convict the defendant of the latter. We turn to the language of the statute, the legislative history, and relevant case law in this analysis.
The intent of the legislature is to be ascertained from the language of the statute if it is plain and unambiguous. State v. Ellis, 197 Conn. 436, 442, 497 A.2d 974 (1985). The state contends that the statutory definition of the offense of operation while impaired authorizes a conviction only when an operator’s blood alcohol ratio falls between the prescribed limits of .07 and .1 percent. State v. Hancich, 200 Conn. 615, 629, 513 A.2d 638 (1986) (Shea, J., concurring).
General Statutes (Rev. to 1985) § 14-227a (b) provided that “[n]o person shall operate a motor vehicle . . . while his ability to operate such motor vehicle is impaired by the consumption of intoxicating liquor. A person shall be deemed impaired when at the time of the alleged offense the ratio of alcohol in the blood of such person was more than seven-hundredths of one per cent of alcohol, by weight, but less than ten-hundredths of one per cent of alcohol, by weight.” (Emphasis added.) General Statutes (Rev. to 1985) § 227a (d) (3) provided that “evidence that at such time the ratio of alcohol in the blood was more than seven-hundredths of one per cent of alcohol, by weight, but less than ten-*222hundredths of one per cent of alcohol, by weight, shall constitute impairment within the meaning of this section . . . .” (Emphasis added.) The statute provides no definition of driving while impaired apart from the blood' alcohol parameters set forth above. The legislature has provided us no definition of impairment in a behavioral context, nor have our courts developed one.
In spite of these clear indications that prosecutions for operating while impaired are warranted only when evidence of a certain blood alcohol content exists, we will turn to the legislative history. In discussing Public Acts 1983, No. 83-534, Senator Howard T. Owens, Jr., stated: “It establishes a new offense of driving while impaired, blood alcohol content of above .07 or below .10 and imposes a penalty of an infraction.” 26 S. Proc., Pt. 13,1983 Sess., p. 4424. Additionally, Representative Christopher Shays stated: “It establishes a new offense called impairment. If someone’s blood alcohol content is between .07 and below .10 that is an offense, an infraction.” 26 H.R. Proc., Pt. 19, 1983 Sess., p. 6676.
From the foregoing, it is clear that the legislature did not intend to establish degrees of intoxication but to provide specifically that the infraction of operation while impaired occurred only when the ratio of an operator’s blood alcohol content fell within certain limits. If we were to read the statute as the defendant desires us to do, the intoxicated driver could seek to avoid the penalty for driving under the influence through simply refusing to take the test and then offering testimony contradicting that of the officer. We are unwilling to do this. There was no evidence that the defendant’s blood alcohol level fell within the parameters set forth in General Statutes § 14-227a (b), and hence the defendant fails the aspect of the Whistnant decision which requires that there be a sufficient evidentiary basis on *223which to instruct the jury on a lesser included offense. Whistnant, supra, 586-88.
Our Supreme Court had occasion to consider whether a lesser included offense instruction of operating while impaired was warranted in a prosecution for driving while under the influence. In State v. Hancich, supra, the defendant’s blood alcohol level was measured at .165 percent. The majority held that there was no error in the trial court’s refusal to instruct the jury on driving while impaired as a lesser included offense because the defendant had introduced no evidence from which a jury could have found that the defendant was impaired as opposed to under the influence. The court did not define impairment or how driving while impaired differs from driving while under the influence, nor did it expressly hold that driving while impaired was a lesser included offense of driving while under the influence.
Here, too, there was substantial evidence that the defendant was under the influence, although his own testimony was that the alcohol he had had to drink did not affect his driving in any way. His testimony conflicted sharply in many respects with that of the police officer who made the arrest, but the import of it was not that his ability to operate was impaired but that his driving was not affected at all by what he had had to drink.
We decline to formulate or adopt a behavioral definition of driving while impaired when the applicable statute, by its very terms, provides that one commits the offense only when one’s blood alcohol ratio falls between .07 and .1 percent.4 In the absence of such evi*224dence, the trier of fact would necessarily have to engage in speculation as to whether a defendant’s behavior reflected a blood alcohol ratio between .07 and .1 percent. On these facts, there was no basis on which to instruct a jury on the offense of operating while impaired.
There is no error.
In this opinion Spallone, J., concurred.
“[General Statutes (Rev. to 1985)] Sec. 14-227a. operation while UNDER THE INFLUENCE OF LIQUOR OR DRUG OR WHILE IMPAIRED BY LIQUOR. (a) operation while under the influence. No person shall operate a motor vehicle on a public highway of this state or on any road of a district organized under the provisions of chapter 105, a purpose of which is the construction and maintenance of roads and sidewalks, or on any private *217road on which a speed limit has been established in accordance with the provisions of section 14-218a, or in any parking area for ten or more cars or on any school property while under the influence of intoxicating liquor or any drug or both.”
“[General Statutes (Rev. to 1985)] Sec. 14-227a. . . . (b) operation while impaired. No person shall operate a motor vehicle on a public highway of this state or on any road of a district organized under the provisions of chapter 105, a purpose of which is the construction and maintenance of roads and sidewalks, or on any private road on which a speed limit has been established in accordance with the provisions of section 14-218a, or in any parking area for ten or more cars or on any school property while his ability to operate such motor vehicle is impaired by the consumption of intoxicating liquor. A person shall be deemed impaired when at the time of the alleged offense the ratio of alcohol in the blood of such person was more than seven-hundredths of one per cent of alcohol, by weight, but less than ten-hundredths of one per cent of alcohol, by weight.”
See Miranda v. Arizona, 384 U.S. 436, 86 S. Ct. 1602, 16 L. Ed. 2d 694 (1966).
We note that General Statutes (Rev. to 1985) § 14-227a (f) provided that evidence of a defendant’s refusal to submit to a blood, breath, or urine test shall, under certain circumstances, be admissible in prosecutions under subsection (a) or (b) of that section. This, the defendant maintains, indicates that the legislature intended the offense of impairment to be provable by other evidence. It is equally likely, however, that the legislature knew that *224blood alcohol evidence which indicates impairment may come from sources other than a test administered by the police, such as a test conducted by a medical expert at the defendant’s request. Impairment could thus be established even though the defendant elected not to take the test provided by the police.