Title: Ralph Schmidt v. Northern States Power Company
Citation: 2007 WI 136
Docket Number: 2005AP001677
State: Wisconsin
Issuer: Wisconsin Supreme Court
Date: December 6, 2007

2007 WI 136 
 
SUPREME COURT OF WISCONSIN 
 
 
 
 
CASE NO.: 
2005AP1677 
COMPLETE TITLE: 
 
 
Ralph Schmidt and Karline Schmidt, 
          Plaintiffs-Appellants, 
 
August C. Heeg, Jr. and Joanne Heeg, 
          Plaintiffs, 
     v. 
Northern States Power Company d/b/a Xcel Energy, 
          Defendant-Respondent-Petitioner, 
 
St. Paul Fire & Marine Insurance Company, 
Associated Electric & Gas Insurance Services 
Limited d/b/a Aegis Insurance Services, Inc., 
and/or Aegis Security Insurance Company, 
          Defendants-Respondents. 
 
 
 
 
 
 
REVIEW OF A DECISION OF THE COURT OF APPEALS 
Reported at: 296 Wis. 2d 935, 724 N.W.2d 273 
(Ct. App. 2006-Unpublished) 
 
 
OPINION FILED: 
December 6, 2007   
SUBMITTED ON BRIEFS: 
        
ORAL ARGUMENT: 
September 11, 2007   
 
 
SOURCE OF APPEAL: 
 
 
COURT: 
Circuit   
 
COUNTY: 
Marathon   
 
JUDGE: 
Jon M. Counsell   
 
 
 
JUSTICES: 
 
 
CONCURRED: 
        
 
DISSENTED: 
        
 
NOT PARTICIPATING:         
 
 
 
ATTORNEYS: 
 
For the defendant-respondent-petitioner there were briefs 
by Michael J. Happe, J. Drew Ryberg, and Ryberg & Happe, S.C., 
Eau Claire, John D. Wilson, Jordan J. Hemaidan, and Michael Best 
& Friedrich LLP, Madison, and oral argument by Andrea B. Niesen 
and Charles A. Bird. 
 
For the plaintiffs-appellants there was a brief by Charles 
A. Bird, Andrea B. Niesen, and Bird, Jacobsen & Stevens, P.C., 
Rochester, MN, and James R. Koby and O’Flaherty Heim Egan, Ltd., 
La Crosse, and oral argument by Charles A. Bird. 
 
 
2 
 
An amicus curiae brief was filed by Trevor J. Will, G. 
Michael Halfenger, and Foley & Lardner LLP, Milwaukee, and Mark 
S. Henkel and First Law Group S.C., Stevens Point on behalf of 
Wisconsin Public Service Corporation and Wisconsin Power and 
Light Company. 
 
An amicus curiae brief was filed by O. Thomas Armstrong, 
William P. Croke, and von Briesen & Roper, S.C., Milwaukee on 
behalf of Wisconsin Electric Power Company. 
 
An amicus curiae brief was filed by H. Dale Peterson, John 
J. Laubmeier, and Stroud, Willink & Howard, LLC, Madison on 
behalf of Wisconsin Farm Bureau Federation, Cooperative. 
 
 
 
 
2007 WI 136
NOTICE 
This opinion is subject to further 
editing and modification.  The final 
version will appear in the bound 
volume of the official reports.   
No.  2005AP1677  
(L.C. No. 
2001CV000191) 
STATE OF WISCONSIN  
 
 
   : 
IN SUPREME COURT 
 
 
Ralph Schmidt and Karline Schmidt, 
 
          Plaintiffs-Appellants, 
 
August C. Heeg, Jr. and Joanne Heeg, 
 
          Plaintiffs, 
 
     v. 
 
Northern States Power Company d/b/a Xcel 
Energy, 
 
          Defendant-Respondent-Petitioner, 
 
St. Paul Fire & Marine Insurance Company, 
Associated Electric & Gas Insurance Services 
Limited d/b/a Aegis Insurance Services, Inc., 
and/or Aegis Security Insurance Company, 
 
          Defendants-Respondents. 
 
FILED 
 
DEC 6, 2007 
 
David R. Schanker 
Clerk of Supreme Court 
 
 
 
 
 
REVIEW of a decision of the Court of Appeals.  Affirmed.   
 
¶1 
ANNETTE KINGSLAND ZIEGLER, J.  This is a review of an 
unpublished decision of the court of appeals,1 which reversed and 
                                                 
1 Schmidt v. Northern States Power Co., No. 2005AP1677, 
unpublished slip op. (Wis. Ct. App. Sept. 28, 2006).  
No. 
2005AP1677   
 
2 
 
remanded the decision of the Clark County Circuit Court, Jon M. 
Counsell, Judge.  The circuit court determined on summary 
judgment that the six-year statute of limitations barred Ralph 
and Karline Schmidt's (Schmidts) claims.  See Wis. Stat. 
§ 893.52 (2003-04).2  The circuit court also concluded at summary 
judgment that the Schmidts' claims were barred by the filed rate 
doctrine.3  The court of appeals reversed and remanded, and 
Northern States Power Company d/b/a Xcel Energy (Northern 
States), petitioned this court for review.  We affirm the court 
of appeals' decision. 
¶2 
The Schmidts filed action in 2001 against Northern 
States alleging that "stray voltage" attributable to Northern 
States caused damage to the health and productivity of their 
dairy herd.4  
                                                 
2 All references to the Wisconsin Statutes are to the 2003-
04 version unless otherwise noted.  Section 893.52 reads: 
An action, not arising on contract, to recover 
damages for an injury to real or personal property 
shall be commenced within 6 years after the cause of 
action accrues or be barred, except in the case where 
a different period is expressly prescribed. 
3 The filed rate doctrine is also known as the filed tariff 
doctrine.  Metro E. Ctr. for Conditioning & Health v. Qwest 
Commc'ns Int'l, Inc., 294 F.3d 924, 927 (7th Cir. 2002).  "[It] 
prohibits a plaintiff from claiming a lower rate than the one 
filed by a regulated entity with the appropriate regulatory 
agency because the filed rate alone governs the relationship 
between the parties."  Prentice v. Title Ins. Co. of Minn., 176 
Wis. 2d 714, 721, 500 N.W.2d 658 (1993).   
4 The 
Public 
Service 
Commission 
of 
Wisconsin 
(PSC), 
investigated and implemented standards regarding "stray voltage 
and its effect on livestock" in 1989 and updated its findings in 
1990 and 1996.  It concluded: 
No. 
2005AP1677   
 
3 
 
¶3 
This appeal presents the following two issues:  First, 
we must decide whether the summary judgment record compels us to 
conclude as a matter of law that the statute of limitations bars 
the plaintiffs' claims.  Northern States asserts that the 
Schmidts' claims are time barred because the summary judgment 
record shows they "discovered" their injury and its cause in 
1993 but did not bring their claim until November 13, 2001, 
which is over six years later.  The Schmidts assert that, while 
the record reflects that they suspected early on that stray 
voltage was negatively affecting their cows, they did not have 
an objective belief that stray voltage from Northern States was 
the cause of their injury until much later.  We hold that where 
the undisputed facts lead to more than one reasonable inference 
about when discovery occurred, summary judgment is not proper.  
Here, more than one reasonable inference about when discovery 
occurred may be drawn from the undisputed facts in the summary 
                                                                                                                                                             
'Stray' voltage is a special case of voltage in which 
the neutral to earth voltage is present across points 
(generally grounded metal objects) in which a current 
flow is produced when an animal comes into contact 
with them. . . . [T]hese contact points can include 
any two conductive points which the animal may 
simultaneously contact to complete a circuit which 
allows current to flow.   
PSC Docket 05-EI-106, at 5 (Amended Order). 
No. 
2005AP1677   
 
4 
 
judgment 
record.5 
 
Therefore, 
summary 
judgment 
is 
not 
appropriate.  
¶4 
Second, we must decide whether the filed rate doctrine 
precludes the plaintiffs' common-law tort claims as a matter of 
law.  Northern States asserts that its filed tariff "gives rise 
to an affirmative obligation of [Northern States], if——and only 
if——the stray voltage exceeds" one milliampere in the "cow 
contact" area due to off-farm sources.  Northern States, 
therefore, concludes that if no evidence shows a measurement 
greater than one milliampere, it cannot be liable because it 
would be a violation of the filed rate doctrine for Northern 
States to act when it does not have an obligation to act under 
its tariff.  The Schmidts claim that the "stray voltage tariff" 
states nothing about damages for stray voltage and does not 
provide a limitation of liability for stray voltage.  Rather, 
the Schmidts argue that the tariff addresses the circumstances 
under which a consumer may ask Northern States to test for stray 
voltage and when Northern States is obligated to provide a 
reduction of stray voltage.  We hold that the filed rate 
doctrine does not bar the plaintiffs' claims because (1) the 
                                                 
5 Gumz v. Northern States Power Co., (No. 2005AP1424), 2007 
WI 135, __ Wis. 2d __, __ N.W.2d __, is also released today.  
Both cases consider the application of the discovery rule in the 
context of stray voltage, but these cases consider different 
aspects of the discovery rule.  Gumz is primarily concerned with 
whether, as a matter of law, the plaintiffs were reasonably 
diligent in attempting to discover their injury and its cause 
whereas this case is primarily concerned with when, as a matter 
of law, the Schmidts actually discovered their injury and its 
cause.   
No. 
2005AP1677   
 
5 
 
Schmidts do not seek a "privilege" within the meaning of the 
filed rate doctrine and (2) as stated in Hoffmann,6 conformance 
with the Public Service Commission of Wisconsin's (PSC) findings 
does not abolish Northern States' common-law duty of ordinary 
care.  
I 
¶5 
In 1978, the Schmidts purchased a dairy farm in Clark 
County, Wisconsin.  They began experiencing problems with their 
dairy herd soon after they purchased the farm.  Their cows, 
including new cows brought to the farm, developed problems such 
as 
mastitis, 
udder 
deformities, 
knee 
ailments, 
breeding 
difficulties, low appetite, low milk production, and unusually 
high mortality. These problems continued to varying degrees 
through 2001 when they filed their claim against Northern 
States.   
¶6 
In the fall of 1992, the Schmidts were experiencing 
problems with their herd and "reaching for reasons."  According 
to Mrs. Schmidt, "somebody suggested that we should call the 
power company for stray voltage, so we called the power 
company . . . ."  On November 24, 1992, a representative from 
Northern States came to the Schmidts' farm to "attempt to detect 
and 
correct 
neutral-to-earth 
or 
stray 
voltage 
concerns."7  
                                                 
6 Hoffmann v. Wisconsin Elec. Power Co., 2003 WI 64, 262 
Wis. 2d 264, 664 N.W.2d 55. 
7 The record contains a permission form, entitled "Agreement 
to Perform a Neutral-to-Earth Voltage Investigation."  The form 
is signed by Ralph Schmidt and dated 11/24/92. 
No. 
2005AP1677   
 
6 
 
Northern States took voltage readings, but it did not find off-
farm sources causing more than one milliampere, the "level of 
concern" 
set 
by 
the 
PSC8 
in 
the 
"cow 
contact"9 
area.  
Accordingly, Northern States told the Schmidts that they did not 
have a problem with stray voltage, and they "would never have 
this problem because [the Schmidts] have plastic water lines."  
Northern States concluded, "no corrective action [was] needed." 
¶7 
In the spring of 1993, the Schmidts again contacted 
Northern States because they "had a miserable winter."  The 
Schmidts told Northern States there has "to be something wrong."  
During the winter, a number of cows died, acquired mastitis, and 
exhibited troubling behavior, such as stomping, slopping at 
drinking cups, and not eating or drinking.  Nothing in the 
record indicates Northern States returned to the farm to conduct 
more stray voltage analysis in response to this call.  During 
                                                 
8 "The 'level 
of concern' above which corrective or 
mitigative action should be taken if production or behavioral 
problems exist is one milliampere steady state in the 'cow 
contact' areas."  PSC Docket 05-EI-106, at 4 (Supplemental 
Findings).  In PSC Docket 05-EI-115, the PSC clarified the 
"level of concern" by concluding that both the farmer and the 
utility 
share 
equal 
responsibility 
for 
stray 
voltage.  
Therefore, the level of concern is two milliampere: the farmer 
is responsible for half, and the utility is responsible for 
keeping its contribution of stray voltage to one milliampere or 
less.  PSC Docket 05-EI-115, at 10-11. 
9 "The most important measurement areas are 'cow contact' 
areas where the animal can simultaneously access two points of 
different 
voltage 
of 
sufficient 
magnitude 
to 
cause 
an 
objectionable current to flow through the animal.  These 'cow 
contact' points or areas primarily include the milking, feed and 
watering areas."  PSC Docket 05-EI-106, at 8 (Amended Order). 
No. 
2005AP1677   
 
7 
 
this time, the Schmidts also called their veterinarian to treat 
their cows.  Although the record does not give an exact date, 
the Schmidts replaced their electric water tanks with plastic 
tanks sometime in 1993, and at some point, the Schmidts attached 
rubber tires to their feed bunks.  
¶8 
Also in the spring of 1993, a representative from 
Dairy Services checked the Schmidts' milking system.  After 
using a "meter of some sort," he told the Schmidts, "you've got 
some current problems here" and "[y]ou should have somebody 
check this out."  The Dairy Services representative suggested 
that the Schmidts contact Northern States and Brian Van Ert 
(Van Ert), an electrician.10   
¶9 
Later in the spring of 1993, the Schmidts hired 
Van Ert to rewire the "whole farm and upgrade[] all the wiring" 
of their on-farm or internal system.  The Schmidts also asked 
Van Ert to assess whether they had problems with stray voltage.  
Van Ert concluded that the Schmidts had a problem with stray 
voltage, and he thought the problem was from Northern States.  
Van Ert called Northern States and told them he "did not think 
                                                 
10 The summary judgment record does not provide a clear 
explanation of Van Ert's qualifications.  It contains no resume, 
previous work experience, and does not definitively state that 
he is a master electrician.  The only mention of his 
qualifications arises out of the deposition questioning of Mrs. 
Schmidt who answered "yes" as to whether Van Ert was a master 
electrician.  This is unlike master electrician Schmidt; the 
record 
contains 
significant 
information 
regarding 
his 
qualifications.  It includes a detailed resume, work experience, 
and a comprehensive report establishing his findings regarding 
the Schmidts' farm.  See ¶20 for a discussion of the facts 
pertaining to master electrician Schmidt.  
No. 
2005AP1677   
 
8 
 
the transformer was large enough" and that "problems started 
when neutral fell to [the] ground in Sept. of 1992."   
¶10 On July 1 and July 22, 1993, Northern States returned 
to the Schmidts' farm to do stray voltage analysis.  However, 
neither test showed that off-farm sources caused voltage 
measurements to exceed the "level of concern" in the "cow 
contact" area. 
¶11 In an August 26, 1993, letter to the Schmidts from 
Northern States, Northern States informed the Schmidts that it 
would be doing "some more grounding work on the lines west" of 
the Schmidts on County Highway C, and it stated that Northern 
States planned to do some deep grounding near the Schmidts the 
week of August 30, 1993.  The letter also stated, "[Northern 
States] would like to get together after this is completed and 
set up another recording session at your farm to determine if 
the effort has had any positive effects."  The letter also 
indicated that Mr. Schmidt had asked to see some of the previous 
test results, but he was told by Northern States to make this 
request in writing. 
¶12 On August 30, 1993, the Schmidts wrote a letter to 
Northern States and requested the "test results from the monitor 
set up in the barn."  Specifically, the Schmidts requested 
voltage-testing results from November 24, 1992, July 1, 1993, 
and July 22, 1993. 
¶13 Sometime between the August 30, 1993, letter and 
September 15, 1993, Mr. Schmidt called the Northern States 
district manager in Abbotsford, Wisconsin.  According to Mr. 
No. 
2005AP1677   
 
9 
 
Schmidt, "I told him I wanted to be released" from Northern 
States' electrical services.11  Mr. Schmidt told Northern States 
he wanted something done; "I've got the test results.  I'm going 
to an attorney."  The district manager, however, asked Mr. 
Schmidt to "give him a few days," and the district manager said 
that he had a "new man on the block." 
¶14 On 
September 
15, 
1993, 
two 
Northern 
States 
representatives came to the Schmidts' farm and conducted another 
stray voltage analysis.  On this date, they found off-farm 
sources that caused voltage measurements to exceed the "level of 
concern" in the "cow contact" area.  Northern States asserts 
that 
these 
results 
occurred 
because 
it 
tested 
under 
a 
hypothetical 
situation. 
 
It 
stated, 
"[t]o 
determine 
'hypothetical' scenarios, [Northern States] temporarily bonded 
the Schmidts' grounding system to barn stanchion steel."  In 
this temporary and hypothetical condition, the cow contact 
measurement did exceed 0.512 volt 60 Hz steady state for tests 
done in 1993, which was over the "level of concern" expressed in 
Northern States' tariff at that time.  Northern States asserted, 
"[a]t no time did [Northern States] measure steady state contact 
voltage 
above 
the 
'level 
of 
concern' 
expressed 
by 
the 
                                                 
11 The "release" that Mr. Schmidt sought would enable him to 
be released from Northern States' services and receive service 
from Clark Electric whose electric line is less than a half mile 
away. 
12 The 0.5 volt, AC, RMS, steady state across a 500-ohm 
resistor in the cow contact area is equivalent to the one-
milliampere "level of concern" set by the PSC. 
No. 
2005AP1677   
 
10 
 
PSC[] . . . during normal farm operations."  It appears Northern 
States and the Schmidts discussed installing an equipotential 
plane13 sometime around this September 15, 1993, testing.  Mr. 
Schmidt said, "after they tested it, they said they'd pay for 
[the equipotential plane] completely."  Northern States asserts 
that it installed the equipotential plane, along with replacing 
some primary neutral conductor and improving some grounding, "to 
eliminate the possibility of exceeding the 'level of concern' 
had the farmer intentionally or inadvertently bonded his 
electrical grounding system to the barn stanchion steel." 
¶15 On September 21, 1993, Mr. Schmidt signed a document 
entitled, "Stray Voltage Reduction Agreement," which listed 
"Equipotential Plane" under modifications.  An invoice dated 
October 
27, 
1993, 
references 
the 
installation 
of 
an 
equipotential 
plane. 
 
After 
the 
equipotential 
plane 
installation, Northern States conducted another stray voltage 
analysis on November 2, 1993.  The test found no off-farm 
sources causing more than one milliampere, the "level of 
concern," 
in 
the 
"cow contact" area.  The herd showed 
improvements after Northern States installed the equipotential 
plane.  However, the cows' health "gradually" began to decline 
                                                 
13 "[A]n equipotential plane may reduce traditional stray 
voltage as measured by cow contact points."  Hoffmann, 262 
Wis. 2d 264, ¶4.  Under § 8.0(d) of Northern States' tariff, 
Northern States should only act to reduce stray voltage, i.e., 
install equipment to reduce stray voltage, when stray voltage 
exceeds 
the 
"level 
of 
concern" 
under 
normal 
operating 
conditions.  
No. 
2005AP1677   
 
11 
 
again during the spring of 1994, and by 1997, the Schmidts' herd 
exhibited similar problems as before.  From the fall of 1993 
until 1997, the Schmidts had no contact with Northern States. 
¶16 In 1997, Northern States contacted the Schmidts to 
inform them it was going to put a "new line in."  Northern 
States increased the size of the neutral line, and the Schmidts 
described things as "bad went to worst."  According to Mr. 
Schmidt, "[b]y [19]97, when they put that new line in.  That -- 
that's when it really went bad.  Before that it was iffy.  You 
know, there was times when I thought it was there but I didn't 
know what to do about it." 
¶17 In December of 1998, the Schmidts were still having 
significant problems with their herd.  Mr. Schmidt again 
contacted Northern States for additional testing and began to 
inquire about an isolator.14  On December 21 and December 30, 
1998, Northern States tested and found no off-farm sources 
causing more than one milliampere, the "level of concern," in 
the "cow contact" area. 
¶18 In January or February of 1999, Northern States 
installed the isolator.  The Schmidts noticed a "[d]rastic 
improvement for a couple months," but in the spring of 1999, 
"[t]errible stuff" began to occur.  Several cows, heifers, and 
calves died in the spring and summer of 1999.   
                                                 
14 Neutral isolation is a method of separating the primary 
and secondary neutrals.  Separation attempts to prevent any off-
farm sources of stray voltage from appearing in a "cow contact" 
area.  PSC Docket 05-EI-115, at 15.   
No. 
2005AP1677   
 
12 
 
¶19 In the spring of 2000, the Schmidts contacted Northern 
States to conduct stray voltage testing.  On March 14, 2000, 
Northern States again tested and found no off-farm sources 
causing more than one milliampere, the "level of concern," in 
the "cow contact" area.  Also, in the spring of 2000, the 
Schmidts' veterinarian, Dr. Jackson, evaluated their herd.  He 
told the Schmidts, "get them out of the barn.  Bring them in to 
milk them and put them outside the rest of the time.  It's stray 
voltage."  Mr. Schmidt told a Northern States representative 
about his veterinarian's opinion and recommendations.  According 
to Mr. Schmidt, in response to the veterinarian's opinion, the 
Northern States' representative told Mr. Schmidt to "get a 
different vet."   
¶20 In the summer of 2001, the Schmidts hired master 
electrician William Schmidt15 to conduct stray voltage analysis.  
Unlike Van Ert, the record is clear that master electrician 
Schmidt had extensive experience with stray voltage testing and 
analysis.  Master electrician Schmidt began stray voltage work 
on dairy farms in 1985.  Over time, he began to use more 
"elaborate recording" equipment for stray voltage testing, and 
by June of 2002, the majority of his time was devoted to stray 
voltage testing and analysis.  Master electrician Schmidt 
generated a comprehensive five-page report for the Schmidts on 
November 3, 2001.  He concluded, "the levels of stray voltage 
                                                 
15 The record contains no evidence that William Schmidt is 
related to Ralph and Karline Schmidt. 
No. 
2005AP1677   
 
13 
 
are substantial enough to create the symptoms seen in the 
Schmidt's dairy herd."  He also concluded that the disconnected 
wire down the road could contribute to much higher levels of 
stray voltage during windy conditions, and the isolation 
provided by Northern States' isolator was inadequate.  In 
addition, he concluded that the primary and secondary ground 
rods were much too close to each other, and the unit could have 
been leaking.  In short, master electrician Schmidt recommended 
that Northern States convert the single-phase line providing 
electricity to the farm to a "Delta" or to a "Phase to Phase" 
operation.   
¶21 On November 13, 2001, the Schmidts filed this lawsuit 
against Northern States.  The initial complaint alleged claims 
of 
negligence, 
strict 
liability, 
nuisance, 
trespass, 
and 
violations of Wis. Stat. chs. 196 and 197, and the Wis. Admin. 
Code § PSC 114.  An amended complaint, filed October 14, 2003, 
removed the claim of trespass.16  Northern States denied the 
allegations and asserted several affirmative defenses.  In 
addition, Northern States moved for summary judgment based upon 
the statute of limitations and the filed rate doctrine.   
¶22 The circuit court granted summary judgment.  It 
concluded that the applicable six-year statute of limitations 
barred the Schmidts' claims because the Schmidts discovered 
                                                 
16 The complaint initially included August and Joanne Heeg, 
the Schmidts' neighbors.  However, the circuit court granted 
Northern States' motion to separate the Schmidts and the Heegs' 
claims. 
No. 
2005AP1677   
 
14 
 
their injury and its cause in 1993.  The circuit court reasoned 
that in 1993 a veterinarian17 and electrician told the Schmidts 
they had a stray voltage problem due to Northern States.  
Moreover, the circuit court, relying on the deposition testimony 
of Mr. Schmidt, concluded that the Schmidts discovered their 
injury and its cause in 1993.18  In addition, the circuit court 
concluded that regardless of the statute of limitations, the 
filed rate doctrine also barred the Schmidts' claims.   
¶23 In an unpublished decision, the court of appeals 
reversed the circuit court on both issues.  On the statute of 
limitations issue, it concluded that the facts do not support 
only one reasonable conclusion about when discovery occurred.  
The court of appeals reasoned that "[e]ven if it is reasonable 
to infer that the Schmidts knew or should have known prior to 
1995 that stray voltage was present on their farm, that does not 
necessarily mean that they also should have known that Northern 
States was the cause of the problem," given Northern States' 
negative test results.  With respect to the filed rate doctrine, 
the court of appeals reasoned that even though Northern States 
had filed a tariff, which described its policies and procedures 
                                                 
17 We find nothing in the record to support the assertion 
that a veterinarian told the Schmidts in 1993 that they had a 
stray voltage problem.  However, a representative from Dairy 
Services did tell the Schmidts around this time that "you've got 
some current problems here" and "[y]ou should have somebody 
check this out."   
18 See footnote 24 for relevant portions of Mr. Schmidt's 
deposition testimony. 
No. 
2005AP1677   
 
15 
 
for responding to customer complaints regarding stray voltage, 
the tariff does not allow the utility to circumvent Hoffmann v. 
Wisconsin Electric Power Co., 2003 WI 64, 262 Wis. 2d 264, 664 
N.W.2d 55.19   
II 
¶24 Whether the circuit court properly granted summary 
judgment is a question of law that this court reviews de novo.  
Green Spring Farms v. Kersten, 136 Wis. 2d 304, 315, 401 
N.W.2d 816 (1987).  This court applies the same standards as 
those used by the circuit court.  Verdoljak v. Mosinee Paper 
Corp., 200 Wis. 2d 624, 630, 547 N.W.2d 602 (1996).  These 
standards are set forth in Wis. Stat. § 802.08.  Summary 
judgment is appropriate only where there is no genuine issue of 
material fact and the moving party is entitled to judgment as a 
matter of law.  Linville v. City of Janesville, 184 Wis. 2d 705, 
714, 516 N.W.2d 427 (1994).  A factual issue is "genuine" if the 
evidence is such that a reasonable jury could return a verdict 
in favor of the nonmoving party.  Baxter v. Wisconsin Dep't of 
Natural Res., 165 Wis. 2d 298, 312, 477 N.W.2d 648 (Ct. App. 
1991).  A "material fact" is one that is "of consequence to the 
merits of the litigation."  In re Michael R.B., 175 Wis. 2d 713, 
724, 499 N.W.2d 641 (1993).  "Any reasonable doubt as to the 
existence of a genuine issue of material fact must be resolved 
                                                 
19 In Hoffmann, the Wisconsin Supreme Court concluded that 
the absence of current above the PSC-established "level of 
concern" does not preclude a farmer from recovering damages from 
a utility for stray voltage injuries attributable to the 
utility.  See Hoffmann, 262 Wis. 2d 264.   
No. 
2005AP1677   
 
16 
 
against the moving party" for summary judgment.  Heck & Paetow 
Claim Serv., Inc. v. Heck, 93 Wis. 2d 349, 356, 286 N.W.2d 831 
(1980).    
¶25 "The question of whether the filed rate doctrine 
shields the defendants from liability is a question of law."  
Prentice v. Title Ins. Co. of Minn., 176 Wis. 2d 714, 721, 500 
N.W.2d 658 (1993).  This court decides questions of law 
independently of the circuit court and the court of appeals.  
Id. 
III 
¶26 Northern States claims the Schmidts discovered their 
injury and its cause in 1993.  Because the Schmidts filed their 
suit on November 13, 2001, Northern States asserts that the 
applicable six-year statute of limitations bars the Schmidts' 
claims.  Northern States argues that Mr. Schmidt's own testimony 
demonstrates an objective belief that stray voltage from 
Northern States was injuring his herd in 1993.  The Schmidts 
take issue with that assertion.  We conclude that different 
reasonable inferences about when discovery occurred can be drawn 
from the undisputed facts in the summary judgment record.  As a 
result, the circuit court erroneously determined as a matter of 
law that discovery occurred in 1993.  
¶27 Section 893.52 of the Wisconsin Statutes prescribes a 
six-year statute of limitations for an action that arises out of 
an injury to property.  Under Wis. Stat. § 893.52, a cause of 
action accrues when the plaintiff discovers, or with reasonable 
diligence should have discovered, the injury and that the 
No. 
2005AP1677   
 
17 
 
defendant's conduct probably caused that injury.  Borello v. 
United States Oil Co., 130 Wis. 2d 397, 411, 388 N.W.2d 140 
(1986); see also 
Hansen v. A.H. Robins Co., Inc., 113 
Wis. 2d 550, 560, 335 N.W.2d 578 (1983).  This court applies the 
discovery rule to "stray voltage cases."  See Kolpin v. Pioneer 
Power & Light Co., Inc., 162 Wis. 2d 1, 25, 469 N.W.2d 595 
(1991).  Discovery occurs when the plaintiff has information 
that would constitute the basis for an objective belief as to 
his or her injury and its cause.  Claypool v. Levin, 209 
Wis. 2d 284, 300, 562 N.W.2d 584 (1997); see also Kolpin, 162 
Wis. 2d at 20-21.  
¶28 However, a plaintiff's subjective or unsubstantiated 
lay belief does not constitute discovery.  Claypool, 209 
Wis. 2d at 300.  Even if the plaintiff knew of his or her injury 
and had a "suspicion or a hunch" as to its cause, discovery does 
not occur until the plaintiff has an objective basis regardless 
of whether her hunch later proves to be correct.  Borello, 130 
Wis. 2d at 414.  Where the cause and effect relationship is not 
readily apparent, a layperson's subjective belief of the cause 
is not sufficient to start the statute of limitations running.  
Id. at 412.   
¶29 This court had the opportunity to examine and apply 
the discovery rule in the context of summary judgment in 
Claypool and Clark.20  Before this court can conclude as a matter 
of law when discovery has occurred, it must determine whether 
                                                 
20 Clark v. Erdmann, 161 Wis. 2d 428, 468 N.W.2d 18 (1991). 
No. 
2005AP1677   
 
18 
 
reasonable inferences with regard to when discovery occurred can 
be drawn from the undisputed facts in the record.  See Cameron 
v. City of Milwaukee, 102 Wis. 2d 448, 459, 307 N.W.2d 164 
(1981).  If conflicting results can be reached, summary judgment 
is not appropriate.  Id.     
¶30 In Clark, Dr. Erdmann performed corrective surgery on 
Ruby Clark's right foot in August of 1981.  Clark, 161 
Wis. 2d at 433.  Clark began to have post-operative problems 
with her right foot, and as a result, she consulted a number of 
other doctors, including Doctors Davey and Kurland, between 
April 1982 and April 1985.  Id. at 434-35.  In September of 
1985, a team, from the same clinic as Dr. Erdmann, performed 
surgery to correct Clark's right foot.  Id. at 435.  Clark knew 
this surgery was to correct Dr. Erdmann's failed surgery; she 
stated that after she spoke to Doctors Davey and Kurland in 1984 
and April of 1985, she realized her foot was in bad shape and 
that it was Dr. Erdmann's fault.  Id.  Clark filed suit in 
February 1987.  This court concluded that, as a matter of law, 
Clark had an objective belief in 1985 as to her injury and its 
cause.  Id. at 449.  The court reasoned that Clark obtained 
verification from Doctors Davey and Kurland that her first 
surgery was unsuccessful.  The court stated, "[t]here being no 
factual disputes or competing inferences to be drawn," summary 
judgment was appropriate.  Id. at 448-49. 
¶31 In Claypool, the plaintiff was urgently admitted to 
the hospital because she suffered from a number of symptoms, 
which included problems with her vision.  Claypool, 209 Wis. 2d 
No. 
2005AP1677   
 
19 
 
at 287.  Between March and April of 1989, Dr. Levin treated 
Claypool's eyes; however, she was permanently blind by March 8, 
1989.  Id. at 287-88.  On April 10, 1989, four days after her 
release from the hospital, Claypool retained counsel, but after 
much delay, he concluded that no suit could be filed.  Id. at 
288.  In 1993, another lawyer determined that a viable medical 
malpractice claim existed.  Id.  Claypool commenced her lawsuit 
well beyond the three-year statute of limitations.  Id. at 289-
91.  This court concluded that summary judgment was appropriate 
because Mrs. Claypool discovered or should have discovered her 
injury between March and April of 1989.21  Id. at 291-302.  The 
court found that Claypool entered the hospital with vision 
problems, was treated by Dr. Levin for approximately one month, 
left the hospital permanently blind, and retained counsel 
shortly after she left the hospital.  Id. at 302.  Based upon 
those facts, and despite receiving incorrect legal advice, this 
court concluded that Mrs. Claypool had an objective basis as to 
her injury and its cause in March or early April of 1989.  Id. 
at 303. 
¶32 In both Clark and Claypool, this court determined that 
the statute of limitations barred the plaintiff's claims.  The 
undisputed facts led to but one reasonable inference about when 
                                                 
21 The circuit court concluded, "the undisputed facts can 
lead to but one reasonable inference, that is, in the exercise 
of reasonable diligence plaintiffs should have discovered the 
probable cause of the injury within a reasonably short period of 
time after the injury."  Claypool v. Levin, 209 Wis. 2d 284, 
289, 562 N.W.2d 584 (1997). 
No. 
2005AP1677   
 
20 
 
discovery 
occurred. 
 
As 
a 
result, 
summary 
judgment 
was 
appropriate.    
¶33 This court applied the discovery rule to a "stray 
voltage" case in Kolpin.22  Even though the jury concluded that 
discovery occurred or should have occurred prior to February 17, 
1981, this court concluded, as a matter of law, that discovery 
did not occur prior to February 17, 1981.  Much like the 
Schmidts, the Kolpins began to notice strange behavior in their 
cattle, such as cows refusing to eat, lapping at their 
"waterers," producing less milk, and experiencing an increased 
incidence of mastitis.  The Kolpins called their veterinarian 
who suggested they contact some experts, but neither the 
equipment expert nor the state veterinarian could find any 
equipment problems.  Kolpin, 162 Wis. 2d at 11-12. 
¶34 Mr. Kolpin bought a voltmeter around 1980 because of 
some articles he read on stray voltage.  Id. at 12.  After 
discovering very high voltage readings in his milking parlor, 
Kolpin called an electrician in 1980 to investigate, but the 
electrician did not know what they meant and suggested that 
Kolpin call the electric company.  Id.  A representative from 
the electric company came to the Kolpin farm, but he did not 
know how or where to measure for stray voltage.  Id.  The PSC 
also sent a representative to the farm.  While he did suggest 
changes to electrical motors and circuitry, which the Kolpins 
                                                 
22 Kolpin v. Pioneer Power & Light Co., Inc., 162 Wis. 2d 1, 
469 N.W.2d 595 (1991). 
No. 
2005AP1677   
 
21 
 
implemented, he did not indicate whether they had a stray 
voltage problem.  Id. at 12-13.   
¶35 In the spring of 1980, the electric company changed 
its distribution system by "driving in twenty additional 
grounding rods on the distribution line that served the farm."  
Id. at 13.  While the voltage levels in the barn dropped 
significantly, the cows' behavior and milk production did not 
change.  Id.  In September of 1983, the Kolpins hired an 
electrical contractor with a background in "stray voltage."  Id. 
at 13-14.  The Kolpins installed an electronic grounding device 
in November of 1983.  Id. at 14.  Following the installation of 
the grounding system, milk production quickly bottomed out but 
then increased to a level equivalent to before the problems 
arose, and the cows' behavior returned to normal.  Id.  Kolpin 
testified, "we weren't sure it was stray voltage or what it was 
until 1983, when the grounding system was installed and the 
voltage levels dropped to their lowest level."  Id.  On January 
16, 1986, the Kolpins wrote a letter to the manufacturer of the 
grounding system: "We are very pleased with the results of your 
electronic grounding system in reducing the stray voltage caused 
by our power company's inability to effectively ground their 
primary neutral system."  Id.   
¶36 The Kolpins filed suit on February 17, 1987, on 
theories of negligence, strict liability, and nuisance.  Id.  
The jury affirmatively found that the Kolpins knew or should 
have known, with the exercise of reasonable care, prior to 
February 17, 1981, that Pioneer's electrical distribution system 
No. 
2005AP1677   
 
22 
 
was a cause of damage to their dairy operation.  Id. at 15.  
This court concluded as a matter of law that the jury should 
have answered "no" to this question instead of "yes."  Id. at 
27.  The court reasoned that while the Kolpins were "aware of 
the concept of stray voltage" by 1980 and had a hunch that stray 
voltage was their problem, they could not tell whether it was 
attributable to Pioneer.  Id. at 26.  The court concluded, 
"[o]nce the problem was remedied, the Kolpins objectively knew 
that Pioneer's distribution system" was the cause of their 
problem.  Id.  "[T]he Kolpins did not discover, or with the 
exercise of reasonable care should not have discovered, prior to 
February 17, 1981, that Pioneer's electrical distribution system 
was a cause of damage to their dairy operation."  Id. at 27.  
¶37 Unlike in Clark and Claypool, in the present case the 
undisputed facts lead to more than one reasonable inference 
about when discovery occurred.  In Kolpin, the plaintiff 
obtained verification23 that his hunch was correct, and only one 
reasonable inference existed about whether discovery indeed 
occurred in November of 1983.  In this case, however, competing 
inferences exist as to whether discovery occurred in 1993.  
Reasonable inferences drawn from the undisputed facts in the 
record could lead a finder of fact to conclude that discovery 
occurred in 1993 or the fact-finder could come to a different 
                                                 
23 This should not be construed to mean that an expert is 
required 
for 
verification. 
 
See 
Fritz 
v. 
McGrath, 
146 
Wis. 2d 681, 690, 431 N.W.2d 751 (Ct. App. 1988) (concluding 
that an expert opinion is not a prerequisite to discovery).  
Verification may occur in many forms.   
No. 
2005AP1677   
 
23 
 
conclusion.  Therefore, summary judgment is not appropriate in 
this case.  
¶38 Northern States reasonably argues that the Schmidts 
had an objective basis as to their injury and its cause in 1993.  
It relies on the following facts: In 1993, the Schmidts' dairy 
consultant urged them to call an electrician because he thought 
they had "some voltage problems."  The Schmidts contacted a 
private electrician to conduct stray voltage testing.  Van Ert 
concluded that the Schmidts had a stray voltage problem and 
thought the problem was from Northern States.  He suggested a 
larger transformer and stated "problems started when neutral 
fell to [the] ground in Sept. of 1992."  Northern States 
asserts, "Mr. Schmidt's deposition testimony makes clear that he 
knew or should have known that his injury existed as early as 
1992 and that he was 'certain' he knew the cause of the 
injury."24   
                                                 
24 In response to deposition questioning, Mr. Schmidt 
testified as follows: 
Q: Okay.  From your study of some of the materials 
back in '93, you were aware that stray voltage could 
be a problem, true? 
A: True. 
Q: You were confident in '93 that stray voltage was a 
problem for you, true? 
A: Yes. 
Q: You were confident that [it] was coming from NSP, 
true? 
A: Yes, I guess. 
No. 
2005AP1677   
 
24 
 
¶39 One reasonable inference drawn from these facts is 
that the Schmidts did indeed discover their injury and its cause 
in 1993.  However, another reasonable inference drawn from these 
facts is that the Schmidts were speculating they had a stray 
voltage problem in 1993 and only had a hunch as to its cause.  
In addition to Mr. Schmidt's deposition testimony cited by 
Northern States, Mr. Schmidt also testified that "[b]y [19]97, 
when they put that new line in.  That -- that's when it really 
went bad.  Before that it was iffy.  You know, there was times 
when I thought it was there but I didn't know what to do about 
it."  When we consider Mr. Schmidt's equivocal statements in the 
                                                                                                                                                             
 . . . . 
Q: Do you now know why the cows started to get sick in 
1992? 
A: 
I 
think 
the 
electric—the 
problems 
with 
the 
electricity just gradually kept getting worst [sic]. 
Q: And approximately when did you become certain that 
it was the problems with the electricity that caused 
the decline of the cows in 1992 and not something 
else? 
A: In '93, when Brian Vanert come out there.  There 
was all kinds of voltage. 
 . . . . 
Q: In 1993, were you confident that stray voltage was 
the cause of all the problems with the cows? 
Mr: Koby: Object to form and foundation.  Go 
ahead. 
A: You can never be a hundred percent confident of 
anything, but in 1993 I knew there was a voltage 
problem.  
No. 
2005AP1677   
 
25 
 
context of all the facts and circumstances, we conclude that the 
undisputed facts lead to more than one reasonable inference 
about when discovery occurred.  
¶40 Consider other relevant facts that also occurred in 
1992 and 1993: At the Schmidts' request, Northern States 
conducted stray voltage testing in November of 1992 and 
concluded that the Schmidts had no stray voltage problem and 
they "would never have this problem because [the Schmidts] have 
plastic water lines."  In the spring of 1993, Van Ert rewired 
the internal system on the farm, but not the external Northern 
States system.  He concluded that the Schmidts had a stray 
voltage problem and suggested that it was from Northern States.  
Van Ert's qualifications, however, are not present in the 
summary judgment record.  Thereafter, in July 1993, Northern 
States conducted more testing and again concluded that no off-
farm sources were causing a stray voltage problem.  In August 
1993, Northern States did some "grounding work" nearby and 
wanted to do more testing when that was completed to see if the 
"effort had any positive effects."  Between August 30, 1993, and 
September 15, 1993, the Schmidts contacted Northern States and 
told them they wished to discontinue Northern States' service, 
and they were going to contact an attorney.  Northern States 
responded by asking for time and telling the Schmidts that 
Northern States had a "new man on the block."  In late 1993, 
Northern States installed an equipotential plane but claimed it 
was a precautionary installation and not installed to reduce 
No. 
2005AP1677   
 
26 
 
stray voltage levels below the "level of concern."25  When 
considering all of the facts and circumstances in 1992 and 1993, 
reasonable persons could conclude that discovery did or did not 
occur in 1993.  
¶41 A competing argument to Northern States' assertion 
that discovery occurred in 1993 is that every time the Schmidts 
moved closer to discovering their injury and its cause, Northern 
States conducted testing and found no stray voltage problem.  
Northern States' repeated testing and conclusions that no stray 
voltage 
problem 
existed 
may 
have 
affected 
the 
Schmidts' 
opportunity to discover their injury and its cause.  Whether 
Northern States' test results affected the reasonable diligence 
of the Schmidts, and hence discovery, is for the jury to 
consider.26  Contemporaneous with Van Ert's findings in 1993, 
Northern States concluded that no stray voltage problem existed, 
                                                 
25 The installation of the equipotential plane produces a 
competing inference:  Northern States claims it can only provide 
stray voltage reduction if stray voltage exceeds the "level of 
concern."  However, an equipotential plane is a device used to 
reduce stray voltage.  Its installation likely violates the 
tariff 
because 
Northern 
States 
claims 
it 
never 
recorded 
measurements that exceed the "level of concern" during normal 
operating conditions.  Thus, one may conclude that stray voltage 
did exceed the "level of concern" if Northern States installed 
an equipotential plane.  However, Northern States claims that it 
only installed the equipotential plane as a precautionary 
measure.  Competing inferences arise.   
26 This 
should 
not 
be 
construed 
that 
the 
court 
is 
establishing a bright line rule that if a potential tortfeasor 
denies a role in the injury and its cause, then discovery can 
never occur.  Discovery can still occur even if the potential 
tortfeasor denies the injury and its cause.   
No. 
2005AP1677   
 
27 
 
and they continued to assert this over the years.27  Northern 
States' continued denial, through negative test results, may 
have bearing on the issue of discovery.  See Jacobs v. Nor-Lake, 
Inc., 217 Wis. 2d 625, 637, 579 N.W.2d 254 (Ct. App. 1998) 
(finding that an official denial by a possible defendant company 
may contribute to competing inferences that a jury must 
resolve). 
¶42 Competing inferences as to when discovery occurred 
continued well past 1993.  By 1997, the Schmidts' herd was 
experiencing the same problems as before, even after Northern 
States installed a new line.  Northern States conducted more 
stray voltage testing in 1998 and again found no stray voltage 
exceeding the "level of concern."  In 1999, Northern States 
installed an isolator, but the herd's health drastically 
declined after just a couple of months of improvement.  Northern 
States conducted another stray voltage test in 2000, but it 
found no stray voltage exceeding the "level of concern."  On the 
other hand, a veterinarian and master electrician concluded in 
the spring of 2000 and summer of 2001 that the Schmidts had a 
                                                 
27 In fact, Northern States seemingly continues to assert 
that no stray voltage problem existed, but it continues to 
assert that the Schmidts discovered or should have discovered 
their injury in 1993.  These conflicting assertions are 
difficult to resolve at summary judgment. 
No. 
2005AP1677   
 
28 
 
stray voltage problem.  Moreover, the master electrician 
concluded that the problem was attributable to Northern States.28 
¶43 The undisputed facts in this case lead to more than 
one reasonable inference about when discovery occurred.  On the 
one hand, Van Ert's conclusions and Mr. Schmidt's deposition 
testimony could lead a fact-finder to conclude that discovery 
occurred in 1993.  On the other hand, Mr. Schmidt's additional, 
equivocal statements about discovery, Northern States' repeated 
negative test results, the Schmidts other efforts to eliminate 
possible causes, and the improvement of the herd's health after 
installing the equipotential plane followed by a decline in the 
herd's health could lead a fact-finder to conclude that 
discovery did not occur in 1993.     
¶44 Northern States further argues that "the Court of 
Appeals has . . . threaten[ed] to extinguish . . . [Northern 
States] substantive, constitutionally based right to dismissal 
on statute of limitations grounds" because it allows the 
Schmidts to "undiscover" their injury and its cause.  In 
Claypool, we corrected the court of appeals' conclusion that 
"'discovery' as a matter of law was not necessarily locked in 
time by [plaintiff's] initial belief given the subsequent 
                                                 
28 While 
the 
record 
contains 
evidence 
that 
discovery 
occurred in 2001 when master electrician Schmidt made his 
findings, we make no determination today as to when the Schmidts 
discovered their injury and its cause.  Likewise, we cannot 
determine as a matter of law whether discovery occurred at an 
earlier time, which would render the possible 2001 "discovery" 
moot. 
No. 
2005AP1677   
 
29 
 
events."  Claypool, 209 Wis. 2d at 301.  Based upon the plain 
meaning of the statute,29 we concluded that an injury and its 
cause cannot be undiscovered.  Id. at 302.  In other words, once 
a person has what would be viewed as an objective belief as to 
his or her injury and its cause, that person is not entitled to 
cast aside that belief because of subsequent events.  Northern 
States asserts that the "Schmidts and their expert, Mr. Van Ert, 
believed in 1993, and continue to believe today, that stray 
voltage was causing Plaintiffs' injury."  Northern States argues 
that "[n]o subsequent events or statements by [Northern States], 
even if they were believed by [the] Schmidts (and the record is 
clear that they were not) can eliminate that discovery."  
¶45 Our decision today does not limit or call into 
question Claypool.  To "undiscover" the injury means discovery 
must have occurred in the first instance.  In this case, we 
cannot determine as a matter of law when discovery occurred 
because more than one reasonable inference about when discovery 
                                                 
29 Wisconsin Stat. § 893.55(1) (1993-94) provides: 
 
(1) Except as provided by subs. (2) and (3), an 
action to recover damages for injury arising from any 
treatment or operation performed by, or from any 
omission by, a person who is a health care provider, 
regardless of the theory on which the action is based, 
shall be commenced within the later of: 
 
(a) Three years from the date of the injury, or 
 
(b) One year from the date the injury was 
discovered or, in the exercise of reasonable diligence 
should have been discovered, except that an action may 
not be commenced under this paragraph more than 5 
years from the date of the act or omission. 
No. 
2005AP1677   
 
30 
 
occurred can be drawn from the summary judgment record.  
Moreover, Northern States can still argue to the trier of fact 
that the Schmidts were not reasonably diligent and that the 
Schmidts discovered their injury and its cause in 1993.   
¶46 Northern States also claims that the court of appeals' 
holding conflicts with the Claypool conclusion that discovery 
may occur even if more than one reasonable cause of the injury 
exists.  We stated in Claypool: 
This court stated in Clark that discovery occurs 
when 
the 
'plaintiff 
has 
information 
that 
would 
constitute the basis for an objective belief of her 
injury and its cause. . . .'  Id.  . . . This does not 
mean that if there is more than one reasonable cause 
of the injury that discovery cannot occur. . . . 
Claypool, 209 Wis. 2d at 300. (Emphasis added.)   
¶47 While the above statement is true, the criteria for 
summary judgment likewise exist.  The rule of law remains that 
if more than one reasonable inference can be drawn from the 
undisputed facts, summary judgment is not appropriate.  Cameron, 
102 Wis. 2d at 459-60.  This court ended the Clark decision with 
the following: "There being no factual disputes or competing 
inferences 
to 
be 
drawn . . . summary 
judgment 
was 
appropriate . . . ."  Clark, 161 Wis. 2d at 449.   
¶48 Lastly, Northern States claims that the court of 
appeals' decision creates a rule that "discovery can only occur 
subsequent to correction of the injury."  However, we conclude 
that discovery may occur before the problem is corrected.  A 
discovery determination may be less complex in cases where the 
injury and its cause are readily apparent.  For example, little 
No. 
2005AP1677   
 
31 
 
time is often required to determine the injury and its cause in 
a car accident.  In many instances, a plaintiff almost instantly 
knows of their injury and its cause.   
¶49 In a stray voltage case, such as the one now before 
the court, a person's discovery of the injury and its cause may 
not immediately arise.  See Kolpin, 162 Wis. 2d at 26 (finding 
that stray voltage does not involve a typical tort claim, such 
as an auto accident, where both the cause and effect are readily 
apparent).  "Because of the difficulties in pinpointing the 
exact source of stray voltage, it is difficult for a plaintiff 
to determine the relationship between the stray voltage and its 
source.  The source could be the plaintiff's own electrical 
wiring, a defect in the milking parlor, or an improperly 
grounded line leading to the barn."  Id. at 26-27.  
¶50 In some stray voltage cases, the plaintiff may have to 
undergo a process of elimination before he or she can discover 
the injury and its cause.30  This, of course, does not mean that 
a process of elimination is required in every stray voltage case 
                                                 
30 This process of elimination may or may not include 
attempts at reducing stray voltage by installing equipment for 
stray voltage reduction, testing by the utility, testing by a 
private expert, veterinarian and nutrition services, or findings 
by other persons knowledgeable about stray voltage.  We do not 
suggest that an individual, in a stray voltage case, cannot form 
an objective basis as to the injury and its cause on his own.  
We merely suggest that when the injury and cause are not readily 
apparent, 
such 
as 
in 
stray 
voltage 
cases, 
a 
discovery 
determination at summary judgment is more difficult.  However, 
as information and technology with regard to stray voltage 
evolves, this may change. 
No. 
2005AP1677   
 
32 
 
or that a stray voltage remedy must occur before a farmer can 
discover it.   
¶51 Because here, competing reasonable inferences can be 
drawn from the undisputed facts, summary judgment is not proper. 
IV 
¶52 This court must now determine whether the filed rate 
doctrine precludes the plaintiffs' common-law tort claims as a 
matter of law.  We conclude that the filed rate doctrine does 
not bar the plaintiffs' claims because (1) the Schmidts do not 
seek a "privilege" within the meaning of the filed rate doctrine 
and (2) as stated in Hoffmann, conformance with the Public 
Service Commission of Wisconsin's (PSC) findings does not 
abolish Northern States' common-law duty of ordinary care.   
¶53 Northern States is required, by statute, to file a 
tariff that specifies the rate at which service will be 
provided, and the utility's rules and regulations that may 
affect that rate and service.  See Wis. Stat. § 196.19(1) and 
(2).  Once Northern States places a tariff on file, it must give 
effect to the tariff under the filed rate doctrine and cannot 
provide services other than those in accordance with the 
tariff.31 
                                                 
31 Section 196.22 of the Wisconsin Statutes represents a 
"statutory expression of the filed rate doctrine."  GTE N. Inc. 
v. Public Serv. Comm'n of Wis., 176 Wis. 2d 559, 569, 500 N.W.2d 
284 (1993).  Wisconsin. Stat. § 196.22 provides: 
No public utility may charge, demand, collect or 
receive more or less compensation for any service 
performed by it within the state, or for any service 
in connection therewith, than is specified in the 
No. 
2005AP1677   
 
33 
 
¶54 Northern 
States' 
tariff 
contains 
the 
following 
relevant provisions in Section 8.0 entitled "Stray Voltage 
Program" with a subheading entitled "Stray Voltage Tariff": 
(a) Under normal operating conditions, a neutral-
to-earth current of voltage may exist on the grounded 
or grounding conductors or other conductive objects on 
the customer's premises.  The source of the current or 
voltage may be located on the premises, off the 
premises, or a combination of both.  Upon the 
customer's 
request, 
the 
Company 
will 
investigate 
inquiries associated with neutral-to-earth current or 
voltage concerns. 
(b) Stray voltage is a 60 Hz steady state AC RMS 
voltage that can be measured across a 500-ohm shunt 
resistor that has been connected between two points 
which livestock may contact simultaneously. . . . 
 . . . . 
(d) Following a determination by the Company 
that, 
under 
normal 
operating 
conditions, 
the 
contributions to animal contact current from off-farm 
sources is in excess of 1.0mA, the Company shall 
implement, at its expense, measures to reduce this 
contribution to below 1.0mA. . . .         
¶55 Northern States argues, under § 8.0(a), that "stray 
voltage may be present on a customer's system as a matter of 
course."  Northern States further argues, under § 8.0(d), that 
its filed tariff "gives rise to an affirmative obligation of 
[Northern States], if——and only if——the stray voltage exceeds" 
one milliampere in the "cow contact" area due to off-farm 
sources.  As a result, Northern States asserts that it cannot be 
                                                                                                                                                             
schedules for the service filed under s. 196.19, 
including schedules of joint rates, as may at the time 
be in force, or demand, collect or receive any rate, 
toll or charge not specified in the schedule. 
No. 
2005AP1677   
 
34 
 
liable unless evidence shows a measurement greater than one 
milliampere, the "level of concern," because it would violate 
the filed rate doctrine for Northern States to provide this 
"service" when it is not required to do so under its tariff.  
Northern States argues that if it provided stray voltage 
reduction when stray voltage levels were below the "level of 
concern," it would be giving the Schmidts more "services" then 
their rate includes.  We disagree and conclude that the terms of 
the tariff do not alter Northern States' common-law duty of 
ordinary care. 
¶56 The purpose of the filed rate doctrine is to avoid 
discriminatory rates and judicial rate-making.  Servais v. Kraft 
Foods, Inc., 2001 WI App 165, ¶12, 246 Wis. 2d 920, 631 
N.W.2d 629.  This court has applied the filed rate doctrine in a 
number of different contexts since 1911.  See Prentice, 176 
Wis. 2d at 723 (summarizing the application of the filed rate 
doctrine in Wisconsin).  The filed rate doctrine seeks to 
enforce the rates and services provided for those rates so that 
all customers are treated uniformly and according to the 
published tariff.  American Tel. & Tel. Co. v. Central Office 
Tel., Inc., 524 U.S. 214, 223 (1998) (AT&T).  It aims to prevent 
a company from intentionally misquoting services as a means to 
hide discounts.  Id.  "[T]he filed rate doctrine prohibits a 
plaintiff from claiming a lower rate than the one filed by a 
regulated entity with the appropriate regulatory agency because 
the filed rate alone governs the relationship between the 
parties."  Prentice, 176 Wis. 2d at 721.  Rates, however, do not 
No. 
2005AP1677   
 
35 
 
exist in isolation; rather, rates have meaning only when one 
knows the services to which the specific rates are attached.32  
AT&T, 524 U.S. at 223.  "Discriminatory 'privileges' come in 
many guises, and are not limited to discounted rates."  Id. at 
224.  
¶57 In AT&T, the United States Supreme Court concluded 
that the filed rate doctrine barred Central Office's state-law 
claims because Central Office sought privileges, i.e., services, 
not in the tariff.  AT&T, 524 U.S. at 226.  Central Office 
brought suit against AT&T for breach of contract and tortious 
interference with contractual relations.  Id. at 216.  Central 
Office 
claimed 
that 
AT&T 
"promised 
various 
service, 
provisioning, and billing options in addition to those set forth 
in the tariff," and Central Office sought those extra services 
even though it previously agreed that services would be governed 
by AT&T tariffs.  Id. at 219-20.  
¶58 The 
Court 
concluded 
that 
faster, 
guaranteed 
provisioning of orders at the price of the published rate was 
"certainly a privilege within the meaning" of the filed rate 
                                                 
32 This court approves of the conclusion in AT&T that the 
filed rate doctrine applies to more than just rates.  American 
Tel. & Tel. Co. v. Central Office Tel., Inc., 524 U.S. 214, 223-
24 (1998) (AT&T).  In AT&T, the Court determined that if it 
applied the filed rate doctrine only to rates, it might not 
prevent advantages given in the form of more services for the 
same dollar.  Discrimination in charges must include non-price 
features, or a party could defeat the purpose of the doctrine.  
Id. at 223.  "An unreasonable 'discrimination in charges' . . . 
can come in the form of a lower price for an equivalent service 
or in the form of an enhanced service for an equivalent price."  
Id.     
No. 
2005AP1677   
 
36 
 
doctrine.  Id. at 225.  Central Office sought to enforce a 
promise that AT&T would provision orders within 30 to 90 days.  
Id.  However, the published tariff left it to AT&T to establish 
and confirm a due date for provisioning.  Id.  Because the 
special provisioning would have given Central Office an extra 
service or privilege not included in the tariff and not offered 
to all customers, the Court concluded that the filed rate 
doctrine barred the plaintiff's claims.  Id. at 226. 
¶59 Unlike the plaintiff in AT&T, the Schmidts do not seek 
a "privilege" within the meaning of the filed rate doctrine.33  
Central 
Office 
sought 
the 
benefit 
of 
time-constrained 
provisioning, which was as an added "perk" not available to 
other customers, whereas the Schmidts seek a common-law duty of 
ordinary care.34  The duty of ordinary care is not a "privilege" 
or "service" that Northern States bestows upon the Schmidts or 
any of its customers.  Northern States' tariff cannot undermine 
that common-law responsibility. 
                                                 
33 Cf. Schmidt with Chicago & Alton R.R. Co. v. Kirby, 225 
U.S. 155, 163 (1912) (concluding that the filed rate doctrine 
barred the plaintiff's claim because the published tariff did 
not provide for expedient shipping, and therefore, the shipper 
received an undue advantage over others); Cahnmann v. Sprint 
Corp., 133 F.3d 484, 487, 490-91 (7th Cir. 1998) (the 
plaintiff's claims were barred because the plaintiff sought 
favorable services——more free calls——under the original tariff 
instead of less favorable services under the amended tariff). 
34 A common-law duty of ordinary care may or may not be 
consistent with the terms of a tariff.  These are considerations 
for a fact-finder. 
No. 
2005AP1677   
 
37 
 
¶60 Northern States claims that stray voltage reduction is 
a 
service——or 
"privilege"——that 
it 
uniformly 
provides 
to 
customers who have stray voltage that exceeds the "level of 
concern."  Northern States argues that it cannot be liable 
unless evidence shows a measurement greater than the "level of 
concern," because it would violate the filed rate doctrine for 
Northern States to provide this "service" when it is not 
required to do so under its tariff.  By accepting Northern 
States' creative legal argument, we would expand the filed rate 
doctrine well beyond its original purpose of ensuring non-
discriminatory rates and services.   
¶61 Traditionally, the filed rate doctrine precluded a 
utility from giving extra-tariff benefits to one customer and 
not offering the same benefits to another.  Stray voltage, 
however, is not a benefit that the Schmidts or any other 
customers desire to receive.  If Northern States is responsible 
for the Schmidts' stray voltage, it cannot claim that reducing 
stray voltage is a "service" or "privilege" that it provides.  
No authority exists for extending the doctrine to circumstances 
where a defendant is allegedly responsible for harming the 
plaintiff, e.g., providing stray voltage, but then claims that 
eliminating the harm is a "service" or "privilege" within the 
meaning of the doctrine.  Because the Schmidts do not seek a 
privilege within the meaning of the filed rate doctrine, it does 
not bar the Schmidts' claims. 
¶62 Northern States asserts that a plaintiff may not 
expand a utility's liability through an action in contract or 
No. 
2005AP1677   
 
38 
 
tort for matters specified in a filed tariff.35  Northern States 
argues that if the Schmidts are successful in their action, 
Northern States' liability will be expanded through tort.  
However, the filed rate doctrine precludes contract claims for 
additional and better services and contract claims disguised as 
tort claims.  In AT&T, the Court dismissed the breach of 
contract claim and the tortious interference with contractual 
relations claim.  As to the tort claim, the Court concluded that 
its "analysis applies with equal force . . . because that [tort 
claim] is wholly derivative of the contract claim for additional 
and better services."  Id. at 226.  Central Office "can no more 
obtain unlawful preferences under the cloak of a tort claim than 
it can by contract."  Id. at 227.  
¶63 Chief Justice Rehnquist elaborated on this point in 
his concurrence and stated that "[t]he acts of tortious 
interference asserted against AT&T amount to no more than an 
intentional refusal to provide services to [Central Office] in 
an amount or manner contrary to the filed tariff."  Id. at 228-
29.  This finding, the Chief Justice wrote, was "necessary to 
the conclusion that [Central Office's] state-law tort claim" 
could not proceed.  Id.  The Chief Justice reasoned that the 
filed rate doctrine disallows suits that are brought in order to 
enforce an agreement to provide services on terms that are 
                                                 
35 Northern States cites to Keogh for the proposition that 
the 
  rights as defined by the tariff cannot be varied or 
enlarged by either contract or tort of the carrier."  Keogh v. 
Chicago & N.W. Ry. Co., 260 U.S. 156, 163 (1922). 
No. 
2005AP1677   
 
39 
 
different from those terms listed in the tariff.  Id.  Chief 
Justice Rehnquist further wrote: 
The tariff does not govern, however, the entirety 
of the relationship between the common carrier and its 
customers. . . . The filed rate doctrine's purpose is 
to ensure that the filed rates are the exclusive 
source of the terms and conditions by which the common 
carrier provides to its customers the services covered 
by the tariff.  It does not serve as a shield against 
all actions based in state law. 
Id. at 230-31 (Rehnquist, C.J., concurring). 
¶64 The bar on certain suits prevents plaintiffs from 
obtaining rates or services through instituting a lawsuit based 
on contract or contract-derived tort claims, such as tortious 
interference with contractual relations or breach of contract 
"disguised" as fraud.  It seeks to preclude a party from 
attempting to enforce an agreement, contrary to the filed rate, 
under the cloak of a tort claim.  Because the Schmidts are not 
seeking extra "services" or "privileges" through contract claims 
or tort claims that are "wholly derivative" of contract claims, 
the Schmidts' common-law tort claims are not barred by the filed 
rate doctrine.  
¶65 The precedent established by Hoffmann supports our 
conclusion that Northern States may not supplant its common-law 
duties in tort through its tariff and the filed rate doctrine.  
This court concluded in Hoffmann that a defendant might still be 
liable even if there are no "cow contact" measurements of more 
than one milliampere, the "level of concern."  Hoffmann, 262 
Wis. 2d 264, ¶13.  In other words, we concluded that a utility's 
No. 
2005AP1677   
 
40 
 
common-law duty of ordinary care is not tied to the PSC's 
findings.36   
¶66 Wisconsin 
Stats. 
§ 196.857 
establishes 
the 
stray 
voltage program.37  In Hoffmann, this court stated, "it is a 
'well-established rule that the enactment of safety statutes or 
legislation giving a commission jurisdiction over a certain 
activity does not abolish the duty arising under common-law 
negligence.'"  Id., ¶12 (citing Kemp v. Wisconsin Elec. Power 
Co., 44 Wis. 2d 571, 579, 172 N.W.2d 161 (1969)).  "'A safety 
statute merely establishes a minimum standard of care and the 
conduct, even though sanctioned or in conformity with the 
statute, is not thereby necessarily relieved of conforming to 
the common-law requirements of ordinary care.'"  Id. (citing 
Blanchard v. Terpstra, 37 Wis. 2d 292, 299, 155 N.W.2d 156 
(1967)).  
                                                 
36 The PSC findings establish a "level of concern," but the 
commission stated, it "will stay apprised of the on-going 
research and will raise or lower this standard as appropriate."  
PSC Docket 05-EI-115, at 1-2.  
37 Wisconsin Stat. § 196.857, 
Stray 
voltage 
program, 
provides in part: 
(1g) 
Program 
elements. (a) The commission shall 
establish and administer a stray voltage program.  The 
program 
shall 
focus 
on 
regulation, 
education, 
inspection 
and 
investigation 
relating 
to 
stray 
voltage. 
(b) The commission shall identify standardized 
test procedures check lists and equipment to be used 
by public utilities to investigate stray voltage. The 
commission may audit the results of investigations. 
No. 
2005AP1677   
 
41 
 
¶67 This court further stated that statutes in derogation 
of the common law are to be strictly construed.  Fuchsgruber v. 
Custom Accessories, Inc., 2001 WI 81, ¶25, 244 Wis. 2d 758, 628 
N.W.2d 833.  "A statute does not change the common law unless 
the legislative purpose to do so is clearly expressed in the 
language of the statute."  Id.  "To accomplish a change in the 
common law, the language of the statute must be clear, 
unambiguous, and peremptory."  We concluded that no language in 
chapter 196 of the Wisconsin Statutes changes common-law 
negligence with respect to stray voltage.38  Hoffmann, 262 
Wis. 2d 264, ¶13.  Therefore, Northern States cannot rely on 
§ 8.0(d) of its tariff to claim that it cannot be liable unless 
stray voltage exceeds the "level of concern."  Northern States 
cannot circumvent Hoffmann by inserting PSC findings——the very 
findings that we decided in Hoffmann do not limit liability——
into its tariff and subsequently claim the filed rate doctrine 
                                                 
38 Changing the common law with respect to stray voltage was 
specifically contemplated and rejected in Wisconsin. 
In Wisconsin's initial budget bill for 2001-2002, a 
provision was included that would have changed the 
standards for civil liability with respect to stray 
voltage.  The bill proposed creating a statute, 
providing that '[a] public utility is immune from 
liability for any damage caused by or resulting from 
stray voltage contributed by the public utility if 
that stray voltage is below the level of concern 
established by the public service commission . . . .' 
2001 S.B. 55, § 3866.  However, after severe public 
criticism, the provision was withdrawn and was never 
passed into law. 
Hoffmann, 262 Wis. 2d 264, ¶13. 
No. 
2005AP1677   
 
42 
 
bars 
liability. 
 
The 
precedent 
set 
in 
Hoffmann, 
which 
established that PSC's standards do not alter the common law, 
remains good law.  Common-law tort liability was not eliminated 
when Northern States inserted the PSC findings into its tariff. 
¶68 Moreover, 
Northern 
States' 
tariff 
contains 
no 
limitation on liability with respect to stray voltage.  Rather, 
Northern States' tariff contains a limitation on liability for 
the regular use of electricity.  Stray voltage does not fall 
under the regular supply of electricity; it does not pass 
through the meter.  Northern States cites to Section 4.6 of its 
tariff to show, generally, that the tariff does contain 
limitations on liability.  Section 4.6 reads: 
Continuity of service.  The Company will use all 
reasonable care to provide continuous service but does 
not 
assume 
responsibility 
for 
a 
regular 
and 
uninterrupted supply of electric service and shall not 
be liable for any loss, injury, or damage resulting 
from the use of service, or arising from or caused by 
the interruption or curtailment of the same. 
This 
provision 
limits 
the 
defendant's 
liability 
for 
the 
plaintiffs' regular use of electricity.  However, no such 
limitation on liability exists with respect to stray voltage.   
V 
¶69 Accordingly, we remand to the circuit court.  We 
conclude that more than one reasonable inference may be drawn 
from the undisputed facts in the summary judgment record about 
when discovery occurred.  Therefore, summary judgment is not 
proper.  We further conclude that the filed rate doctrine does 
not bar the plaintiffs' claims because (1) the Schmidts do not 
No. 
2005AP1677   
 
43 
 
seek a "privilege" within the meaning of the filed rate 
doctrine, and (2) as stated in Hoffmann, conformance with the 
PSC's findings does not abolish Northern States' common-law duty 
of ordinary care.     
By the Court.—The decision of the court of appeals is 
affirmed. 
 
 
No. 
2005AP1677   
 
 
 
1