Corey T. Denevan


Corey Denevan is an experienced attorney that truly cares about his clients. He takes time to listen to their concerns and helps them accomplish their goals. Corey handles transactional work such as drafting Wills, durable powers of attorney, all types of trusts, family limited partnerships, LLCs, real estate transactions and business planning. Corey provides guidance with respect to administration issues arising in trust, probate, guardianships and conservatorship matters. Corey represents both professional and individual trustees, executors, guardians and beneficiaries navigate their way through difficult situations. Corey has both trial and appellate experience.

Corey enjoys representing local South Dakotans as well as individuals, attorneys, advisors, public and private trust companies all over the United States who choose to avail themselves of South Dakota trust laws. Corey is also available to serve as a mediator in estate, trust and guardianship matters, providing families a discrete and private setting to resolve their disputes.


Corey was born and raised in Sioux Falls, South Dakota. However, he began his professional career on the West Coast in Seattle, Washington. He was an assistant vice president and trust officer with one of the nation’s largest financial institutions. Corey transitioned to the practice of law at Hertog & Coster, PLLC where he focused on estate planning, probate administration and the representation of non-professional fiduciaries and professional fiduciaries, such as banks, trust companies and guardianship agencies. Corey joined Aiken, St. Louis & Siljeg, P.S. as a shareholder, where he continued to manage complex trust, estate and guardianship matters, but also expanded his practice into business planning and succession, real estate transactions, creditor rights and commercial litigation. Corey also served as court appointed trustee and personal representative in complex and contentious cases.

Corey was a longstanding member of the Washington State Bar Association’s Real Property & Probate Section and Guardianship and Elder Law Section, as well the King County Bar Association’s Real Property & Probate Section and Elder Law Section. Corey served two terms on the executive committee of the King County Bar Association’s Elder Law Section. In 2005, Corey was nominated and served as the chair of a committee with judges and court commissioners to draft forms to be used by guardians and trustees to report on their fiduciary activities. In 2012, Corey was nominated and served as co-chair of the Washington State Bar Association’s task force to revise the Uniform Durable Power of Attorney Act to reduce financial exploitation of vulnerable and elderly persons.

After twelve years on the West Coast, Corey and his wife returned to Sioux Falls to be closer to their families. Upon returning to Sioux Falls, Corey served as an adjunct professor at a local university teaching employment law.

Corey joined Boyce Law Firm, LLP in 2013 where he focuses on trust, probate and guardianship matters as well as estate and gift tax planning. He continues to be a frequent presenter at continuing legal education seminars for lawyers. He also continues his legislative activity by serving on a task force for the South Dakota Bar Association to revise the Uniform Durable Power of Act for implementation in South Dakota, and has drafted and advocated for proposed legislation to implement dispute resolution procedures to all contested trust, probate and guardianship cases.


Augustana University – Sioux Falls, South Dakota (BA Biology, 1996)
Academic Scholarship Recipient
Athletic Scholarship Recipient Football, NCAA Div. II

University of Missouri – Columbia, Missouri (JD 2000)
Opal A. Carlson Academic Scholarship
CALI Legal Excellence for the Future Award – Secured Transactions
Accommodation for Excellence in Agricultural Law

Professional and Community

• South Dakota Bar Association
• Second Circuit Bar Association
• Washington Bar Association
• King County Bar Association
• United States District Court Western District of Washington

Publications and Presentations

2017 NBI Trusts From A to Z “Ethical Considerations for Lawyers in Trust Matters”

2017 NBI Trusts From A to Z “Special Needs Trusts”

2016 NBI Estate Administration From Start to Finish: “Handling Estate Administration Tax Issues”

2016 NBI Estate Administration From Start to Finish: “Distribution and Closing of the Estate”

2015 NBI Trusts 101: “Estate Planning for the Disabled Client”

2015 NBI Trusts 101: “Ethical Considerations for Lawyers”

2012 Washington State Bar Association: Legislative Committee
“Presentation of Revisions to Uniform Durable Power of Attorney Act”

2012 Washington State Bar Association: Paralegal Studies Seminar “New Changes to Washington Trust Act”

2012 Washington State Bar Association: RPPT Mid-Year Meeting “Revising the Uniform Durable Power of Attorney Act: Balancing Individual Autonomy and Protection from Financial Abuse”

2011 Title 11 Guardianship Guardian ad Litem Training “Less Restrictive Alternatives to Guardianship”

2011 King County Bar Association: Advanced Issues in Fiduciary Law: “Current Developments in Fiduciary Law”

2011 NBI Probate and Estate Administration: “Ethical Challenges in Estate Administration”

2011 Washington State Bar Association: Avoiding Elder Law Malpractice “Client Representation and Fee Agreements”

2011 Washington State Bar Association: “New Changes to Washington Trust Act”

2010 King County Bar Association: Advanced Guardianship Issues “Payment of DSHS/DDD Guardian and Attorneys Fees” Co-presented with Washington Attorney General’s Office

2009 National Business Institute: Sophisticated Probate Strategies “Procedural Updates” and “Preventing and Litigating Probate Disputes”

2009 Washington Association of Professional Guardians: “Payment of Guardian’s Fees and Costs from DSHS”

2008 King County Bar Association: Guardianship and Elder Law Section:
“Bankruptcy & Guardianships: What You Need to Know”

2008 National Business Institute: Oddities and Challenges in Probate Law: “Probate Litigation” and “Solutions to Special Issues”

2006, 2007 & 2008 Title 11 Guardianship Guardian ad Litem Training: “Less Restrictive Alternatives to Guardianship”

2007 Washington State Professional Guardian Certification Training: “Guardian of the Estate Issues”

2007 Half Moon LLC, Continuing Education: Washington Estate Planning and Probate Practice for Paralegals: “Assisting in the Administration of the Probate Process”

2006 NBI The Probate Process from Start to Finish: “Litigating the Case in Probate Court”

2005 Washington State Professional Guardian Certification Training: “Prudent Investor Rule”

2004 Washington State Bar Association Establishing, Managing and Terminating the Special Needs Trust: “Termination of Special Needs Trusts”

2003 National Business Institute: “Drafting and Managing Special Needs Trusts”

2003 King County Bar Association Advanced Minor Settlements Guardian ad Litem Program: “Presentation on Special Needs Trusts”

2002 Wells Fargo Bank Seminars on Estate Planning and Special Needs Trusts

2002 Orange County Bar Association (California) Trustee Panel Discussion: “Management of Special Needs Trusts”.

2002 Presentation to Iowa Trial Lawyers: “Drafting and Managing Special Needs Trusts.”

Mediator's Bio

During my time at the University of Missouri – Columbia School of Law, each course had a component to develop skills in negotiation, mediation, arbitration and problem solving, which began the development of my interest in alternative dispute resolution. A majority of the cases that I have been involved in over the last seventeen years involved mandatory mediation and a few cases required arbitration. I have become adept and fond of the process of mediation and arbitration. The subject matter of most of my cases, and the cases I have been called to mediate are as follows:

• Will contests
• Durable powers of attorney
• Trusts
• Estate, gift and income tax issues
• Probate administration
• Elder abuse and neglect
• Guardianships
• Fiduciary duties
• Inter-family disputes involving
–     Business succession planning
–     Farm succession planning
–     Caring for the elderly or disabled
• Partnership and corporate governance
• Contractual matters involving
–     Real estate transactions
–     Franchises
–     Employment

The skills necessary to successfully mediate a case do not always require an expertise in a particular field of law. Mediation is more about developing an understanding the interests of the parties and finding opportunities for resolution.

While I have litigated numerous cases through trial and appeal, my most gratifying work has been in the area of alternative dispute resolution. Serving as a mediator or representing a client in mediation and creating a forum for the parties to control and craft their own resolution is very gratifying.  I have witnessed how the mediation process can provide a catharsis for clients resulting in a better outcome that is not necessarily achievable through traditional litigation. I have also found that arbitration can provide a more expedient, efficient, cost effective means of resolving a dispute in private.