Given how the Spanish media treats everything royal related with kids gloves, sometimes its hard for foreigners to get what’s really going on.
One of the big arguments about the succession law has been whether the previous king will maintain his absolution constitutional immunity from civil and criminal lawsuits. As far as I know, the king hasn’t committed any crimes, so why is this such a big deal?
The big deal is that Spanish succession law makes no difference between illegitimate and legitimate heirs, and two lawsuits has been filed claiming paternity, one of which by a son older than the Felipe. The judge dropped the case due to the immunity of the king.
If the king loses immunity, then the other son could claim paternity and the right to be the next king, which would make ridicules the whole succession process.
However, since the king’s current immunity comes from the constitution, it’s not quite that easy to maintain it without fiddling with a bunch of laws, which could potentially be overruled by the courts and create a giant mess.
Once Felipe has been proclaimed, the law says he won’t lose his job if the illegitimate son gets his day in court, but before this happens, no one really knows. Hence, the big rush to get this done as soon as possible.