The Oklahoma Bar Journal January 2026

The Oklahoma Supreme Court has not addressed in-marriage enhancement to any significant extent since the Thielenhaus decision in 1995. Cases regarding in-marriage enhancement have been left to the Oklahoma Court of Civil Appeals, which is not in a position to alter Thielenhaus .

that case, the husband opened a business in his name just prior to the parties’ marriage. It was undisputed that the value of the business increased in value by at least $584,000 and perhaps by as much as $2.8 million during the parties’ six-year marriage. 43 It was undisputed that the wife expended significant time actively working for the business but was not paid for her labor. 44 It was further undisputed that the husband “undertook tremendous efforts during the marriage directly related to the operation and growth of the business.” 45 The husband was “described essentially as the keyman and sole executive – ran the company, controlled its direc tion, met with its customers and communicated regularly with its bankers.” 46 At trial, two expert witnesses presented significant valuation testimony. 47 The husband appears to have relied in substantial part on the wife’s inability to meet the burden – including a claimed inability to recall the wife’s contri butions as an employee, which the

the appreciation was primarily passive. Those cases were then summarized, perhaps unclearly, in a 1979 law review note. This new shifting burden approach was adopted by Templeton , apparently believing it was derived from settled Oklahoma law. Later, the Hardaway opinion reframed the shifting burden approach and imposed the burden of proof solely on the nonowning spouse without discriminating between primar ily active and primarily passive appreciation. Then, Thielenhaus adopted the version of this rule set out in Hardaway and tied that burden to a series of elements that effectively created a presumption that all growth on separate assets during marriage is separate prop erty. None of the authors appeared to have intended to affect a change to existing law; rather, they all appeared to believe they were sim ply restating settled Oklahoma law. Thus, the shift in this rule appears to have occurred by inadvertence and accident rather than through careful judicial consideration.

THIRTY YEARS OF THIELENHAUS

As noted by Professor Spector in 1988, “The burden of proof is usually determinative.” 41 Cases in which inequitable results occur as a result of Thielenhaus ’ pre sumption are underrepresented in published case law. However, in unpublished cases and anecdot ally amongst practitioners, there is concern that the presumption leads to inequitable results, partic ularly with respect to businesses actively managed by one or both parties. Requiring the party with the least knowledge or access to information to bear the burden of proof seems inherently unfair. Comparatively, the owning spouse has knowledge of the asset, the operations of the business, access to the accounts, access to docu ments, relationships with employ ees and other information relevant to a Thielenhaus analysis. An excellent illustration of the inherent flaws in the burden of proof rule can be seen in the recent case of Williams v. Williams . 42 In

Statements or opinions expressed in the Oklahoma Bar Journal are those of the authors and do not necessarily reflect those of the Oklahoma Bar Association, its officers, Board of Governors, Board of Editors or staff.

20 | JANUARY 2026

THE OKLAHOMA BAR JOURNAL