Checkbox

<fieldset class="usa-fieldset-inputs usa-sans">
    <legend>Historical figures 1</legend>
    <ul class="usa-unstyled-list">
        <li>
            <input id="truth" type="checkbox" name="historical-figures-1" value="truth" checked>
            <label for="truth">Sojourner Truth</label>
        </li>
        <li>
            <input id="douglass" type="checkbox" name="historical-figures-1" value="douglass">
            <label for="douglass">Frederick Douglass</label>
        </li>
        <li>
            <input id="washington" type="checkbox" name="historical-figures-1" value="washington">
            <label for="washington">Booker T. Washington</label>
        </li>
        <li>
            <input id="carver" type="checkbox" name="historical-figures-1" value="carver" disabled>
            <label for="carver">George Washington Carver</label>
        </li>
    </ul>
</fieldset>

<!-- Validation - Error -->
<fieldset class="usa-fieldset-inputs usa-input-error">
    <legend>Historical figures 2</legend>
    <span class="usa-input-error-message" id="input-error-message" role="alert">Helpful error message</span>
    <ul class="usa-unstyled-list">
        <li>
            <input id="truth" type="checkbox" name="historical-figures-1-error" value="truth" checked>
            <label for="truth">Sojourner Truth</label>
        </li>
        <li>
            <input id="douglass" type="checkbox" name="historical-figures-1-error" value="douglass">
            <label for="douglass" class="usa-input-error-label">Frederick Douglass</label>
        </li>
        <li>
            <input id="washington" type="checkbox" name="historical-figures-1-error" value="washington">
            <label for="washington">Booker T. Washington</label>
        </li>
        <li>
            <input id="carver" type="checkbox" name="historical-figures-1-error" value="carver" disabled>
            <label for="carver">George Washington Carver</label>
        </li>
    </ul>
</fieldset>