For the appellant there were briefs by Peter M. Gennrich and  Jenswold, Studt, Hanson, Clark & Kaufman of Madison and oral argument by  Mr. Gennrich.
      For the respondent the cause was argued by Albert Harriman,  assistant attorney general, with whom on the brief was Bronson C. La Follette,  attorney general.
COFFEY, J.
      Two issues are presented for review:
      1. Whether the trial court erred when, on its own motions,  it permitted the state after resting to reopen its case in order to supply the  court with expert testimony as to the reliability and accuracy of the MR-7?
      2. Whether the Circuit Court erred in reversing the County  Court's determination that judicial notice could not be taken as to the  reliability and accuracy of the MR-7?
      [1]
      The issue as to whether the trial judge can reopen a party's  case for further testimony after the party has rested is important in  determining the scope of the record from which this court makes its review. If  the trial court improvidently reopened the case for further testimony, this  court would be obliged to determine this case without the benefit of the expert  testimony given at the continued hearings. We do not find the trial court in  error in this respect. It has been consistently held that a litigant has no  automatic right to reopen a case in order to produce additional testimony, but  this limitation is not applicable to the trial court. The court may on its own  motion reopen for further testimony in order to make a more complete record in  the interests of equity and justice. Diener v. Heritage Mut. Ins. Co.,37 Wis.2d  411, 422, 151 N.W.2d 721 (1967); In re Estate of Javornik,35 Wis.2d 741, 746,  151 N.W.2d 721 (1967). This rule promotes efficient judicial administration in  avoiding another trial due to an incomplete record.
      As to the second issue, the expert testimony received at  trial indicated that both the stationary radar and moving radar devices rely on  the same scientific principle known as the Doppler effect. Webster's Third New  International Dictionary defines the Doppler effect as a scientific principle  in the following manner:
 
  "A change in the frequency with which waves [as sound,  light, or radio waves] from a given source reach an observer, the frequency  decreasing with the speed at which source and observer move away from each  other and increasing with the speed at which they move toward each other so  that the pitch of a sound is apparently raised or lowered as the source and the  observer move toward or away from each other. . ."
      In a speeding conviction based upon a stationary radar  instrument, a legal explanation of the Doppler effect and its application in  speed radar was presented in East Cleveland v. Ferrell,168 Ohio St. 298, 154  N.E.2d 630 (1958) at 631:
  "The radar speed detecting devices commonly used in  traffic control operate on what is known as the Doppler Effect and utilize a  continuous beam of microwaves sent out at a fixed frequency. The operation  depends upon the physical law that when such waves are intercepted by a moving  object the frequency changes in such a ratio to the speed of the intercepted  object that, by measuring the change of frequency, the speed may be  determined."1
      Many states have held that judicial notice can be taken as  to the reliability and accuracy of stationary radar due to the scientific  acceptance of the soundness of the Doppler effect.2 47 A.L.R.3d 822,  "Proof, by Radar or Other Mechanical or Electronic Devices, of Violations  of Speed Regulations."
      The moving radar is a relatively recent innovation and at  the time of the arrest in this case, moving radar had only been in use in  Wisconsin for three months. Moving radar is claimed to have advantages over the  traditional stationary radar which is mounted to a parked police car. The  moving radar, on the other hand, can be used in tracking the speed of a car  traveling in the opposite direction from a moving squad car. While both radar  units employ the Doppler effect, the difference from stationary radar is that  two frequency beams are emitted instead of just one. The moving radar's second  beam is used to determine the patrol car's speed. The moving radar contains  computer components which determine the speed of an oncoming car by subtracting  the speed of the moving patrol car from the closing rate of the oncoming car to  the patrol car.
      To this court's knowledge, the State of Ohio is the only  jurisdiction in the nation which has permitted the taking of judicial notice as  to the reliability and accuracy of a moving radar unit. State v. Shelt,46 Ohio  App.2d 115, 346 N.E.2d 345 (1976). A New York court in People v. Cunha,93  Misc.2d 467, 402 N.Y.S.2d 925 (1978) did not directly address the issue before  this court, but held a speeding conviction using an untested moving radar  device can uphold a conviction for speeding when the speed of the alleged  violator can be supported by the testimony of qualified observers. A law  enforcement officer was found to be a qualified observer. Supra at 926.
      This case is indeed novel in raising a challenge as to  whether judicial notice can be taken as to the reliability and accuracy of a moving  radar device. Its novelty is heightened by the fact that Wisconsin has never  directly ruled upon whether judicial notice can be accorded the accuracy and  reliability of any speed radar device. The Circuit Court opinions found there  was no reason to distinguish the moving radar from a stationary machine. These  decisions relied on State v. Trailer Service, Inc.,61 Wis.2d 400, 212 N.W.2d  683 (1973) in finding that judicial notice had been taken as to the reliability  of stationary radar and the same treatment should be given to moving radar  devices. The reliance on State v. Trailer Service, Inc., supra, is misplaced  for it was stated at 408:
  "A scientific or medical method not recognized as  acceptable in the scientific or medical discipline as accurate does not enjoy  the presumption of accuracy, i.e., liedetector tests. See cases cited at Anno.  (1952), Physiological or Psychological Truth and Deception Tests, 23 A.L.R.2d  1306, 1308, sec. 2; State v. Bohner (1933), 210 Wis. 651, 246 N.W. 314; LeFevre  v. State (1943), 242 Wis. 416, 8 N.W.2d 288; State v. Perlin (1955), 268 Wis.  529, 68 N.W.2d 32. But tests by recognized methods need not be proved for  reliability in every case of violation. Examples, speedometer, breathalyzer,  radar. See cases cited at Anno. (1973), Speeding—Proof—Radar, 47 A.L.R.3d 822,  831, sec. 3; see also: Anno. (1967), Intoxication —Tests—Statutes, 16 A.L.R.3d  748; 46 A.L.R.2d 1176; 127 A.L.R. 1513; 7 Am. Jur.2d, Automobiles and Highway  Traffic, p. 878, sec. 334. These methods of measurement carry a prima facie  presumption of accuracy. Whether the test was properly conducted or the  instruments used were in good working order is a matter of defense. The  administration of law would be seriously frustrated if the validity of basic  and everyday accepted tests had to be a matter of evidence in every case in the  first instance."
      [2]
      The clear wording of the court's opinion in the Trailer  Service case is that there is a "prima facie presumption" as to the  accuracy of radar. A prima facie presumption is a very different legal creature  than a fact for which judicial notice can be taken.
      Sec. 902.01(2), Stats., indicates the type of facts upon  which judicial notice may be taken:
"KINDS OF FACTS. A judicially noticed fact must be one  not subject to reasonable dispute in that it is either (a) generally known  within the territorial jurisdiction of the trial court or (b) capable of  accurate and ready determination by resort to sources whose accuracy cannot  reasonably be questioned."
      As stated in the Federal Advisory Committee Notes published  with the Wisconsin Code of Evidence in 56 Marq. L. Rev. 155 at 170, as to  judicially noticed facts, "[A] high degree of indisputability is the  essential prerequisite." Additionally, in Fringer v. Venema,26 Wis.2d 366,  132 N.W.2d 565 (1965), it was established that expert testimony could be given  in aiding a court in taking judicial notice. At 372 it was stated:
  "`Courts will take judicial notice of  "scientific" facts which have been well established by authoritative  scientists and are generally accepted as irrefutable by living  scientists."
      Based upon the standards of Fringer v. Venema, supra, the  court finds in this case that neither authoritative scientists nor irrefutable  scientific fact was presented.
      The state called as an expert witness William Goodsen, an  engineering manager for Custom Data Communications, Inc. Goodsen's employer  manufactures the "moving radar" used by the State Patrol. Goodsen is  a trained engineer who has done post-graduate study. It was Goodsen's testimony  that the MR-7 is virtually always accurate all but one percent of the time. To  his knowledge the only road condition affecting the accuracy of the MR-7 was  the traffic condition where a large truck would pass the squad car; the reading  for the squad would be affected, but usually in the motorist's favor.
The defense called Jerry Schroeder, an electronics engineer  with West Bend Autotronics, a competitor of Custom Data. Schroeder has a  two-year degree in engineering and has nine years practical experience in the  field. He testified as to the results of tests he had run with a State Patrol  MR-7.
      He found the MR-7 to be inaccurate 15 to 20 percent of the  time. The inaccuracy usually resulted on twolane highways where traffic is  congested or where the roadside is heavily covered with trees or signs.  Schroeder stated that the MR-7's inaccuracy usually resulted from an incorrect  patrol car speed being registered. The error in the patrol car speed was found  to be as much as 20 m.p.h. slow, and this in turn caused a higher speed being  calculated for the oncoming car. The tests were conducted under conditions  where a calibrated speedometer was not used, and speed was determined by  time-distance calculations from stop watch readings.
      Apart from the Circuit Court's conclusion that State v.  Trailer Service, Inc., supra, had accorded judicial notice to stationary radar  devices, when the testimony of these experts is put against the testing  standards of authoritative irrefutability, judicial notice should not have been  taken. Sec. 902.01(2), Stats.; Fringer v. Venema, supra. Frequently, persons  appearing as experts who are business competitors to one another in a limited  market area lack the independent judgment required of an authoritative expert.  Further, we find no challenge in the record to the expertise of Jerry  Schroeder, and, although his tests were conducted under adequate scientific  conditions, these test conditions were hardly in conformity to optimum  scientific procedures. The existence of credible, conflicting expert testimony  refutes the idea that the accuracy of the MR-7 was indisputable. Despite  Schroeder's failure to conduct his testing of the MR-7 under optimum scientific  conditions, we do not find his testimony incredible as a matter of law.3  Therefore, due to the conflicting expert testimony, judicial notice should not  have been taken as to the MR-7's reliability and accuracy.
      Given that the law in Wisconsin at the time of trial was  that a prima facie presumption could be accorded the accuracy of speed radar,  the existence of credible, conflicting expert testimony becomes an issue of  fact. The County Court sitting without a jury as the trier of fact found the  defense testimony persuasive and ruled for the defendant. We find in this case  based upon the record that the reviewing Circuit Court should not have reversed  the trial court on an issue of fact dealing with the credibility of the  witnesses when there is credible evidence which under any reasonable view  fairly admits of an inference which supports the verdict. Jacobs v. Stack,63  Wis.2d 672, 676, 218 N.W.2d 364 (1974). Since we have found the defense  testimony not to be incredible as a matter of law, the trial court's finding of  not guilty should have been affirmed. If one accepts the defense testimony as  credible that the inaccuracy of the MR-7 results from an incorrect calculation  of the patrol car speed, it is persuasive to finding the defendant not guilty  in that Trooper Holl failed to establish the use of the "verify  button" on this particular occasion. The "verify button" permits  the patrolman by utilizing the radar's memory function to ascertain the exact  reading on the squad's speed as entered into the radar's speed equation. The  reading on the squad's speed then can be manually checked against the squad  car's calibrated speedometer. In light of the expert testimony as to the  potential inaccuracy of the calculation of the patrol car's speed, we find the  use of the "verify button" and other testing techniques important  safeguards in ascertaining an accurate radar reading.
      Consequently we hold, that as to the MR-7 used on the date  in question, the state not only failed in showing that judicial notice should  be taken as to its reliability and accuracy, but that it failed to carry its  burden of proof in the prosecution of a speeding citation based upon a speed  reading from an MR-7 radar device.
The court takes this opportunity to establish guidelines for  the prosecution of speeding citations issued on the basis of a moving speed  radar device. The courts of this state may take judicial notice of the  reliability of the underlying principles of speed radar detection that employs  the Doppler effect as a means of determining the speed of moving objects. To  this end, expert testimony is not needed to determine the initial admissibility  of speed radar readings. The radar reading may be introduced by the operating  law enforcement official, if he is qualified in its use and operation.
      The accuracy of any speed radar device is another matter.  The accuracy of the most indisputable scientific theory is subject to its  application in particular conditions. The application of any virtually  undisputed scientific fact to the immediate surrounding conditions must be  explained in ascertaining its accuracy.
      [3]
      Consequently, in Wisconsin a prima facie presumption of  accuracy sufficient to support a speeding conviction will be accorded to moving  radar upon testimony by a competent, operating police officer that:
      1. The officer operating the device has adequate training  and experience in its operation.
      2. That the radar device was in proper working condition at  the time of the arrest. This will be established by proof that suggested  methods of testing the proper functioning of the device were followed.
      3. That the device was used in an area where road conditions  are such that there is a minimum possibility of distortion.
      4. That the input speed of the patrol car must be verified,  this being especially important where there is a reasonable dispute that road  conditions may have distorted the accuracy of the reading (i.e., presence of  large trucks, congested traffic and the roadside being heavily covered with  trees and signs).
      5. That the speed meter should be expertly tested within a  reasonable proximity following the arrest and that such testing be done by  means which do not rely on the radar device's own internal calibrations.
      We do not foresee these conditions to proving a prima facie  speeding case will place an onerous burden upon the law enforcement of speeding  violators. We believe these conditions are necessary to maintaining and  improving the public confidence in the law enforcement and judicial systems.  For the average law abiding American citizen, minor traffic offenses constitute  the only contact such a person will have with the law enforcement and judicial  systems. Public confidence rests upon the fairness of such proceedings. Until a  radar device is invented that is accurate under any conditions, fairness  dictates that contested prosecutions are conducted according to meaningful  standards which insure the instrument's accuracy.
      [4]
      By the Court.—Judgment reversed and case remanded for  proceedings not inconsistent with this opinion.

