# Challenging a transaction

With Aragon Govern's **optimistic governance model**, every transaction has a **delay period** (you can read more [here](https://legacy-docs.aragon.org/products/aragon-govern/why-do-transactions-require-a-delay-period-in-order-to-be-executed)) allowing the community time to review and decide if there are actions described that might be contrary to the DAO agreement.

During this delay period **transactions may be challenged**, and if challenged a dispute is created in [Aragon Court](https://legacy-docs.aragon.org/products/aragon-court) (or any other preferred dispute resolution system specified in the DAO).

{% hint style="warning" %}
If you do not agree with a transaction that has been scheduled, provide a clear justification so that guardians can understand why you are disputing it. This will greatly increase case comprehension for the guardians and allows for faster dispute resolution.
{% endhint %}

![](https://d33v4339jhl8k0.cloudfront.net/docs/assets/5c98a4fe0428633d2cf3fcf7/images/6113ed15b55c2b04bf6dd6a2/file-hd6ZlldfSY.png)

{% hint style="danger" %}
**VERY IMPORTANT NOTE!!!**

* When you challenge a transaction, \*\*you need to add \*\*<mark style="color:blue;">**collateral**</mark> to the challenge. The collateral token and amount are defined in the DAO settings.
* When creating a challenge, **you also need to pay the court fees** in <mark style="color:blue;">**DAI**</mark>, which will be used to pay guardians and actors on the dispute.

So for challenging a transaction you need to have both these tokens on your wallet:

1. The <mark style="color:blue;">**collateral token**</mark>
2. <mark style="color:blue;">**DAI**</mark> token
   {% endhint %}