This isn’t just a fight over one property’s value. It raises a much bigger question: What happens when taxpayers challenge the system itself?
I have been following this fight for more than two years.
I first came across Mitchell Vexler’s battle with the Denton Central Appraisal District (DCAD) in 2024. What I found caught my attention enough that I began digging deeper—not only into what was happening in Denton County, Texas, but into a much more basic question:
Could similar problems exist here in Washington?
That question sent me down a path I never expected.
I began researching Washington’s property-tax system, mass appraisal, assessment methodology, constitutional uniformity requirements, administrative rules, appeal procedures, and the enormous amount of complexity involved in determining the assessed values upon which our property taxes are based.
Then I started looking closer to home.
I began examining King County assessment data and individual parcels. I compared similarly situated properties. I researched how mass-appraisal models are developed and tested. I filed public-records requests. I examined appeal outcomes and evidentiary standards. Eventually, I went through the property-tax appeal process myself.
The deeper I went, the more questions I had.
What began in 2024 as curiosity about one property-tax fight in Texas ultimately became years of my own research into the property-tax system here in Washington—particularly King County.
It is also a significant part of what ultimately led me to run for King County Assessor.
I didn’t decide to run because I had spent my career inside the assessment system.
I decided to run because I had spent years examining it from the outside—as a property owner, taxpayer, researcher and advocate—and became convinced that we need to be willing to ask much harder questions about whether the system is actually producing the fair and uniform results the public is told it produces.
And now, remarkably, the very case that helped start that journey for me has reached the doorstep of the United States Supreme Court.
The Case Has Reached the Supreme Court — But There’s an Important Distinction
The case is Mitchell Vexler, et al. v. Don Spencer, Chief Appraiser, Denton Central Appraisal District, et al., U.S. Supreme Court No. 26-179.
A petition for a writ of certiorari was filed August 5, 2026, and the Supreme Court docketed the case on August 10. The petitioners also filed a motion asking the Court to expedite consideration. DCAD and Don Spencer waived their right to respond, while another respondent, Mavex Shops of Flower Mound, filed a brief supporting the petition.
There is an important distinction here:
The Supreme Court has not yet agreed to hear the case on its merits.
Docketing a petition is not the same thing as granting certiorari. The Justices must still decide whether they will hear the case.
Recently, Real Estate Mindset brought renewed attention to the fight through two videos discussing the Supreme Court filing. Having followed Vexler’s work since 2024, seeing the case reach this stage immediately caught my attention again.
Real Estate Mindset — Supreme Court is About to Break Property Tax
Real Estate Mindset — Supreme Court Just Accepted a Property Tax Fight
For anyone who wants to dig into the history and supporting material rather than just watch commentary about it, Vexler and Mockingbird Properties have assembled an extensive repository of litigation documents, presentations, reports, evidentiary materials and their own analysis. The site traces the lawsuit back to October 2023, an amended petition in April 2024, an appeal in December 2024, subsequent appellate proceedings and ultimately the current Supreme Court petition.
Mockingbird Properties — DCAD Case & Research Repository
The Mockingbird materials make extremely serious allegations—including allegations of fraud and systemic misconduct. Those are allegations and arguments advanced by Vexler and Mockingbird, and I am not presenting them here as judicially established facts.
But that does not mean citizens shouldn’t examine them.
Read the documents. Examine the evidence. Look at the methodology. Look at the government’s responses. Then ask whether the results withstand scrutiny.
That’s exactly what transparency should allow citizens to do.
What Happens When the Problem Isn’t One Assessment — But the System?
Most property owners understand the basic concept of a property-tax appeal.
Government assigns your property a value.
You think the value is wrong.
You appeal.
You present evidence supporting a different value.
But what happens when the taxpayer isn’t simply saying:
“You got my number wrong.”
What happens when the taxpayer is saying:
“The system producing these numbers is itself the problem”?
That distinction is at the heart of why I’ve followed this case for so long.
The Supreme Court petition presents two questions, the first of which asks whether due process permits a state to make an administrative remedy exclusive when the designated tribunal allegedly lacks the authority to grant the prospective relief sought—potentially leaving the property owner without a state court capable of adjudicating that claim.
Put more simply:
Can government require you to challenge it through a particular process while simultaneously preventing that process from deciding the challenge you’re actually making?
That is a question every property owner should care about.
Having an Appeal Process Does Not Automatically Mean You Have Meaningful Due Process
Property owners are routinely told that if they disagree with an assessment, they have a remedy:
Appeal it.
But the mere existence of an appeal process should never end the inquiry.
We should also ask whether a taxpayer can present evidence relevant to the actual issue being raised.
Can the decision-maker consider a challenge involving uniformity rather than merely market value?
Can systemic problems be examined, or is the process limited to changing one property’s number for one year?
Can taxpayers meaningfully question the methodology producing their assessments?
What remedies are actually available?
How long does the process take?
And what happens when the taxpayer’s evidence suggests that the problem extends beyond one parcel?
Due process must be meaningful, not merely procedural.
Government cannot prove citizens have meaningful recourse simply by pointing to the existence of an appeal form.
That issue particularly resonates with me because of what I have encountered while researching and navigating Washington’s own property-tax system.
Texas law is not Washington law. The administrative structures aren’t identical, and I am not suggesting the legal claims in Vexler automatically apply here.
I am saying that the questions are worth asking here too.
This Is Why Mass Appraisal Deserves Scrutiny
County assessors have an enormous job.
King County contains hundreds of thousands of parcels. Government obviously cannot conduct a complete traditional individual appraisal of every property every year, so mass-appraisal systems use sales data, property characteristics, statistical analysis and valuation models to value large populations of property.
The existence of mass appraisal isn’t itself evidence of wrongdoing.
But neither should the phrase “mass appraisal” become a shield against scrutiny.
If a system is capable of generating hundreds of thousands of assessed values, then we should also be capable of evaluating the hundreds of thousands of results it produces.
Are similarly situated properties actually being treated similarly?
Are there significant unexplained disparities?
Do certain categories of property repeatedly produce unusual results?
When discrepancies appear, are they investigated?
When taxpayers identify legitimate errors, are those errors corrected?
Or does the system become focused on defending the assessment simply because the government produced it?
Those aren’t anti-government questions.
They’re accountability questions.
Uniformity Should Be Demonstrated Through Results
One of the issues that has increasingly concerned me through my research is the difference between saying a methodology is intended to produce uniformity and demonstrating that its actual results are uniform.
Those are not necessarily the same thing.
Statistical studies and ratio analyses have an important role in mass appraisal. They can provide useful information about the overall performance of a valuation system.
But an acceptable aggregate statistic should never become the end of the inquiry.
A system can look one way when viewed from thirty thousand feet and very different when you begin examining individual properties, neighborhoods, land classifications or groups of similarly situated parcels.
That is why I believe property-assessment systems should be subjected to comprehensive and transparent auditing that goes deeper than asking whether an aggregate statistic falls within an acceptable range.
If government claims its assessment system produces uniform results, government should be willing to demonstrate it through the results.
Who Watches the Watchers?
And that leads to another question that I believe deserves considerably more attention:
Who audits the system itself?
Who independently asks whether valuation models are producing the results they are supposed to produce?
Who identifies recurring discrepancies?
Who examines whether appeal outcomes reveal patterns?
Who investigates when taxpayers repeatedly identify the same problems?
Who determines whether the oversight mechanisms themselves are working?
And when systemic problems are discovered, who has both the authority and willingness to correct them?
Interestingly, Mockingbird’s current materials have evolved toward this same institutional question. One of its recent reports is literally titled “Who Watches the Watcher?” and focuses on appraisal review boards, oversight and the ability of existing institutions to adjudicate structural claims.
That question matters far beyond Texas.
Government cannot be accountable only to itself.
And transparency isn’t government publishing a conclusion and asking the public to trust it.
Transparency means providing enough information that someone outside the institution can independently examine how that conclusion was reached.
Property Taxation Is Not Beyond Constitutional Scrutiny
This is also occurring during a broader period of serious litigation over government and property rights.
The Supreme Court has dealt with major questions involving property-tax foreclosure and government retention of property value in recent years. The legal issues in those cases differ from Vexler, but the underlying principle is important:
The government’s authority to tax property does not place the property-tax system beyond constitutional scrutiny.
Neither should the enormous complexity of modern assessment systems insulate those systems from public scrutiny.
Complexity makes transparency more important, not less.
Washington Property Owners Should Be Asking Questions Too
Again, Vexler arises from Texas.
This article is not an argument that Texas law governs Washington or that everything alleged in Denton County is occurring in King County.
But the case that first caused me to start researching these issues also caused me to ask questions that I believe Washington property owners deserve answers to.
When a Washington property owner believes an assessment is wrong, we tell that person there is an appeals process.
Fine.
But let’s keep asking questions.
Does that process provide meaningful due process?
Can taxpayers effectively present evidence relevant to uniformity?
Are evidentiary standards logical and consistently applied?
Are taxpayers able to understand how their assessments were actually produced?
Can recurring or systemic problems be identified through individual appeals?
Can legitimate errors be corrected quickly rather than requiring taxpayers to spend enormous amounts of time fighting government?
Does government proactively search for discrepancies?
Or does the burden fall largely upon individual taxpayers to discover them?
These questions are not theoretical to me anymore.
I’ve gone through the property-tax appeal process myself.
I’ve examined assessment records and comparable properties. I’ve researched valuation methodologies. I’ve filed public-records requests. I’ve looked at assessment and appeal data. I’ve compared properties that the system says should be treated according to principles of uniformity.
And I’ve learned something important along the way:
The public should never be afraid to ask government to prove that its systems are producing the results government claims they produce.
Government Should Have to Show Its Work
If an assessment system is accurate and uniform:
Show us.
If a mass-appraisal model works:
Show us the results.
If similarly situated properties are being treated uniformly:
Demonstrate it.
If an appeal system provides meaningful due process:
Show us through its procedures and outcomes.
If an oversight system is working:
Show us what it is finding.
And when the evidence demonstrates that something isn’t working:
Fix it.
Government is not inherently correct simply because government made the original decision.
Admitting an error is not a failure of government.
Refusing to correct one is.
Property owners should never be told to “trust the system.”
Government is always to be continuously challenged, never inherently trusted.
The Case Has Come a Long Way — But the Supreme Court Hasn’t Decided Whether It Will Hear It
As I write this on September 7, 2026, Vexler v. Spencer is officially before the United States Supreme Court as No. 26-179.
The petition for certiorari has been filed and docketed. A motion for expedited consideration was filed. One respondent has waived a response, while another has filed a brief supporting the petition. But the Supreme Court has not yet granted certiorari or agreed to decide the merits of the case.
The Court could ultimately decline to hear it.
Or it could take the case.
I will certainly be watching.
Because for me, this isn’t simply another Supreme Court case that appeared in the news.
It’s where much of this journey started.
A case I began following in 2024 caused me to start asking questions about my own state’s property-tax system. Those questions led me deeper into Washington law, King County assessment practices, mass appraisal, uniformity, public records and the appeals process.
And ultimately, they contributed to my decision to run for King County Assessor.
Two years later, the original fight has made its way to the highest court in the country.
Whatever happens next, I believe the underlying question is one every property owner in America should be willing to ask:
When government tells you that you have a right to challenge it, is there actually somewhere you can go to have that challenge meaningfully heard?
Because rights that exist only on paper aren’t enough.
Neither is accountability that exists only in theory.
Fairness. Transparency. Truth. Accountability.
For the People.
And when a system isn’t producing the results the law and the public deserve:
A New System Will Rise.
Read the Case & Follow the Research
U.S. Supreme Court — Official Vexler v. Spencer Docket, No. 26-179
Mockingbird Properties — DCAD Case, Evidence & Research Repository
Real Estate Mindset — Supreme Court is About to Break Property Tax
Real Estate Mindset — Supreme Court Just Accepted a Property Tax Fight