Senate Bill 459
Admissibility of expert witness testimony
Topics: Court: Procedure, Witness
Became law
The governor signed it on Mar 9, 2026. It's .
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Introduced, passed
Oct 2, 2025
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Committee, passed
Approved
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Senate vote, passed
Passed Nov 18, 2025
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Assembly vote, passed
Passed Jan 22, 2026
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Governor, passed
Signed
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Law, here now
2025 Wisconsin Act 92
Latest entry in the official record, Mar 9, 2026: “Published 3-7-2026”
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The same bill was also filed in the Assembly as AB 458. That version died when the session ended.
Terms on this page
Wisconsin Act
The number a bill gets when it becomes law, like 2025 Wisconsin Act 12.
Official term: Act. More in the glossary
Legislative Reference Bureau
The Legislature's nonpartisan office that drafts bills and writes the summary at the top of each one.
Official term: LRB analysis. More in the glossary
Author
A lawmaker who formally puts a bill forward. The text itself is drafted by the Legislative Reference Bureau.
Official term: Author, coauthor. More in the glossary
Signed on in support
Lawmakers who back a bill without being one of its authors, often from the other chamber.
Official term: Cosponsor. More in the glossary
Roll call
A vote where each lawmaker's yes or no is recorded by name.
Official term: Roll call vote. More in the glossary
What it does
Summary by the , the Legislature's nonpartisan drafting office. It's their wording, not ours.
This bill updates the current statutory rule of evidence relating to testimony by experts to conform with recent changes made to Federal Rule of Evidence (FRE) 702 intended to clarify the court’s gatekeeping role with respect to expert testimony. Current law parallels FRE 702 prior to its amendment, allowing the testimony of an expert witness if the witness’s scientific, technical, or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact at issue in the case, but limiting the testimony of an expert witness to testimony that is based on sufficient facts or data, that is the product of reliable principles and methods, and that is based on the witness applying those principles and methods reliably to the facts of the case. Similar to the changes made to FRE 702, the bill confirms that the proponent of the testimony is required to demonstrate to the court that it is more likely than not that the witness’s testimony is based upon sufficient facts or data, that it is the product of reliable principles and methods, and, finally, that the witness’s opinion reflects a reliable application of those principles and methods to the facts of the case.
Who's behind it
4 senators are its . All 4 are Republicans.
12 more lawmakers .
See all 16 names Hide the names
Authors (4)
- Dan Feyen · Republican, Senate
- Howard Marklein · Republican, Senate
- Van Wanggaard · Republican, Senate
- Eric Wimberger · Republican, Senate
Signed on in support (12)
- Brent Jacobson · Republican, Assembly
- Cindi Duchow · Republican, Assembly
- Rob Kreibich · Republican, Assembly
- Clint Moses · Republican, Assembly
- Dave Murphy · Republican, Assembly
- Jeff Mursau · Republican, Assembly
- Jerry O'Connor · Republican, Assembly
- Will Penterman · Republican, Assembly
- Jim Piwowarczyk · Republican, Assembly
- Paul Tittl · Republican, Assembly
- Nancy VanderMeer · Republican, Assembly
- Bob Wittke · Republican, Assembly
How lawmakers voted
There was one vote on this bill.
Senate Committee on Judiciary and Public Safety vote to recommend it
Passed, 8 to 0 · Nov 12, 2025
No member-by-member record exists for this vote. Committee votes and some older sessions record totals only.
Official motion: “Report passage recommended by Committee on Judiciary and Public Safety, Ayes 8, Noes 0”. Official record · This vote on its own page
What happened
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Mar 9, 2026
The new law was published.
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Mar 9, 2026
The governor signed it. It became 2025 Wisconsin Act 92.
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Mar 5, 2026
Sent to the governor.
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Jan 22, 2026
The Assembly passed it too.
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Jan 16, 2026
Sent to the Assembly Committee on Rules.
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Nov 19, 2025
The Assembly received it.
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Nov 18, 2025
The Senate passed it.
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Nov 12, 2025
The committee voted to recommend passing it, 8 to 0.
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Oct 22, 2025
The committee held a public hearing.
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Oct 2, 2025
Sent to the Senate Committee on Judiciary and Public Safety.
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Oct 2, 2025
Introduced in the Senate.
See the official record, word for word Hide the official record
- Oct 2, 2025 · Senate
Introduced by Senators Wanggaard, Feyen, Marklein and Wimberger; cosponsored by Representatives B. Jacobson, Kreibich, Moses, Murphy, Mursau, O'Connor, Penterman, Piwowarczyk, Tittl, VanderMeer, Wittke and Duchow
- Oct 2, 2025 · Senate
Read first time and referred to Committee on Judiciary and Public Safety
- Oct 22, 2025 · Senate
Public hearing held
- Nov 12, 2025 · Senate
Executive action taken
- Nov 12, 2025 · Senate
Report passage recommended by Committee on Judiciary and Public Safety, Ayes 8, Noes 0
- Nov 12, 2025 · Senate
Available for scheduling
- Nov 14, 2025 · Senate
Placed on calendar 11-18-2025 pursuant to Senate Rule 18(1)
- Nov 18, 2025 · Senate
Read a second time
- Nov 18, 2025 · Senate
Ordered to a third reading
- Nov 18, 2025 · Senate
Rules suspended to give bill its third reading
- Nov 18, 2025 · Senate
Read a third time and passed
- Nov 18, 2025 · Senate
Ordered immediately messaged
- Nov 19, 2025 · Assembly
Received from Senate
- Jan 16, 2026 · Assembly
Read first time and referred to committee on Rules
- Jan 20, 2026 · Assembly
Placed on calendar 1-22-2026 by Committee on Rules
- Jan 22, 2026 · Assembly
Rules suspended to withdraw from calendar and take up
- Jan 22, 2026 · Assembly
Read a second time
- Jan 22, 2026 · Assembly
Ordered to a third reading
- Jan 22, 2026 · Assembly
Rules suspended
- Jan 22, 2026 · Assembly
Read a third time and concurred in
- Jan 22, 2026 · Assembly
Ordered immediately messaged
- Jan 22, 2026 · Senate
Received from Assembly concurred in
- Jan 28, 2026 · Senate
Report correctly enrolled
- Mar 5, 2026 · Senate
Presented to the Governor on 3-5-2026
- Mar 9, 2026 · Senate
Report approved by the Governor on 3-6-2026. 2025 Wisconsin Act 92
- Mar 9, 2026 · Senate
Published 3-7-2026
Terms on this page
Wisconsin Act
The number a bill gets when it becomes law, like 2025 Wisconsin Act 12.
Official term: Act. More in the glossary
Legislative Reference Bureau
The Legislature's nonpartisan office that drafts bills and writes the summary at the top of each one.
Official term: LRB analysis. More in the glossary
Author
A lawmaker who formally puts a bill forward. The text itself is drafted by the Legislative Reference Bureau.
Official term: Author, coauthor. More in the glossary
Signed on in support
Lawmakers who back a bill without being one of its authors, often from the other chamber.
Official term: Cosponsor. More in the glossary
Roll call
A vote where each lawmaker's yes or no is recorded by name.
Official term: Roll call vote. More in the glossary
From the Wisconsin Legislature's official record, checked Sep 15, 2026. See the source
Wisconsin Act
The number a bill gets when it becomes law, like 2025 Wisconsin Act 12.
Official term: Act
Legislative Reference Bureau
The Legislature's nonpartisan office that drafts bills and writes the summary at the top of each one.
Official term: LRB analysis
Signed on in support
Lawmakers who back a bill without being one of its authors, often from the other chamber.
Official term: Cosponsor
Roll call
A vote where each lawmaker's yes or no is recorded by name.
Official term: Roll call vote