How to create new object from interface without knowing the explicit type in Go?

The problem is that once the concrete type and value are extracted from the interface, it contains a pointer to the original object. Any changes to the extracted object affect the original object. This then makes the following equal comparison useless because essentially they are pointing to the same value.

func (r *TestRequest) AssertJSONResponseBody(expectedObj interface{}, mesgAndArgs ...interface{}) bool {
    outObject := reflect.Indirect(reflect.ValueOf(expectedObj)).Addr().Interface()
    err := json.NewDecoder(r.Recorder.Body).Decode(outObject)

    if err != nil {
        return assert.Error(r.t, err)
    }

    return assert.Equal(r.t, expectedObj, outObject, mesgAndArgs...)
}

How do I create a new instance of the underlying type without coupling it to the original value via a pointer?