Detailed answer — how to challenge an application under Idaho law

1. Understand the legal framework

Probate and administration in Idaho are governed by Idaho Code Title 15 (Probate and Affidavits). That title sets out who may be appointed, order of priority, required oath and bond, and court procedures for appointment and oversight. For statute text and chapter organization see Idaho Code Title 15: https://legislature.idaho.gov/statutesrules/idstat/Title15/.

2. Who may challenge and why

Usually blood relatives and interested persons (creditors, beneficiaries, or someone claiming a superior right to appointment) may file an objection. Common legal grounds for contesting an appointment include:

• The applicant is not the person entitled by Idaho’s priority rules to serve.
• The applicant is legally disqualified (e.g., lacks capacity, is under guardianship, convicted of certain crimes, or is insolvent and cannot post bond).
• Evidence of undue influence, fraud, or misrepresentation around the death, the application, or a will.
• Failure to give legally required notice or improper service to interested parties.
• A valid will exists that names a different personal representative.

3. Practical step‑by‑step procedure

1. Confirm the filing and get the case number. Go to the district court clerk in the county where the decedent’s estate is being probated and ask for the probate docket or file. You need the case number and the exact name of the pleadings filed by your sibling.
2. Check deadlines and immediate relief options. File an objection as soon as possible. If letters have already issued and you fear loss or waste of estate assets, ask the court for emergency relief (temporary restraining order or trustee appointment) to protect assets while the dispute is decided.
3. File a written objection or competing petition. Your document can be titled an “Objection to Petition for Letters of Administration” or a “Petition for Appointment” if you are seeking appointment yourself. Serve copies on the applicant and all required parties following court rules.
4. Request a hearing and state your grounds. In the objection or petition, ask for a hearing and clearly list the factual and legal reasons the court should deny (or revoke) the sibling’s application. Attach any supporting evidence or identify witnesses.
5. Gather evidence. Collect documents: death certificate, medical records, communications showing undue influence, financial records showing mismanagement, prior wills, and proof of your relationship and priority. Prepare witness lists and affidavits where appropriate.
6. Attend the hearing and present testimony. At the hearing you or your lawyer will present evidence and legal argument. The court will consider Idaho law, the decedent’s wishes (if a will exists), the applicant’s qualifications, and the best interest of creditors and beneficiaries.
7. Ask for bond, inventory, and accounting. Even if the sibling remains appointed, you can ask the court to require an adequate bond and to compel an inventory and periodic accounting to protect estate assets.

4. What if there is a will?

If a valid will exists that names a personal representative, that appointment ordinarily controls. If your sibling applied as administrator because there was no will, but a will surfaces later, file a notice of the will with the court and ask the court to revoke letters issued under intestacy rules and admit the will (if valid) and appoint the fiduciary named in the will.

5. If you want to be appointed instead

If you believe you have priority under Idaho law (for example, you are a higher priority heir or the nominated representative in a will), file a competing petition asking the court to appoint you and explain why the sibling should not be appointed. The court will decide based on evidence, statutory priority, and qualification.

6. Evidence and procedural tools

Useful procedural tools include subpoenas for records or witnesses, motions for temporary orders (to freeze distributions or protect assets), and requests for bond and inventory. Keep careful records of all communications with the decedent before death, medical providers, financial institutions, and the applicant.

7. Timeframes and practical notes

There is no uniform one‑size‑fits‑all schedule—district courts handle probate matters and each county may have local practices. Because the court may issue letters quickly to authorize access to assets, move promptly. If you delay, the court may be less likely to unwind actions already taken by a properly bonded representative.

8. Where to find Idaho statutes and probate forms

Start with Idaho Code Title 15 (Probate and Affidavits) for statutory rules that govern appointment and administration: https://legislature.idaho.gov/statutesrules/idstat/Title15/. For local procedures and forms, contact the clerk of the district court in the county where the decedent lived. The Idaho Judicial Branch and county court clerks can provide guidance on filing and service requirements.

Helpful hints

• Act quickly. Probate matters move fast; earlier intervention gives you more options.
• Get the probate case number and read the filed petition — know exactly what was requested.
• Document everything. Preserve emails, texts, letters, and financial statements that support your position.
• Do not take possession of estate property on your own. Let the court or appointed representative handle assets unless the court orders otherwise.
• Consider filing a competing petition if you have higher priority or a better claim to appointment.
• Ask the court to require a bond and an inventory if you are concerned about asset protection.
• Subpoena records early when documents are held by third parties (banks, doctors, employers).
• If the sibling already took funds or property improperly, mention that at your hearing and present evidence supporting return or surcharge claims.
• Consult a probate attorney if possible. Probate litigation has procedural complexity and local practice variations.