The Finnish government enacted a law in the beginning of 2008 which allows the Finnish police to build a list of websites to be censored by teleoperators if they contain illegal child pornography.
A large amount of web pages added to the censorship list by the Finnish police are hosted in servers which are located inside the EU and the USA. By adding these websites to the censorship list they are proclaiming that they contain illegal child pornography.
If these websites, hosted in servers inside the EU and the USA, indeed contained illegal child pornography, the proper course of action would be, naturally, for the Finnish police to contact the proper authorities in those countries so that these websites would be closed and the owners prosecuted. The Finnish authorities work together with the authorities inside the EU and the USA (and many other countries) to fight CP, so it would be natural for them to contact the authorities of the other country. However, they are not doing that. They are simply adding these websites to the censorship list and doing nothing else.
Why? Why would they claim that the websites contain illegal CP but not contact the authorities of the hosting country so that something would be done about it? It would be egregiously irresponsible for them to do nothing about this illegal material, even though they have the means to do something about it.
The only possible answer to this question is that they actually know the material is not illegal, and that contacting the authorities of those other countries would be a waste of time. And indeed, the vast majority of websites in the censorship list only contain adult pornography. While it might be indecent in the eyes of many people, there's still nothing illegal about it.
The new Finnish censorship law does not give the authorities the right to censor legal material, only illegal. Yet they are censoring legal material (and they even fully aknowledge that, even if indirectly, by the fact that they are not contacting the authorities of the hosting country to bring the websites down).
The reason for this is probably as "innocent" as them just wanting to show that "something is being done". The censorship list would probably be very short if they were only censoring material which was truly illegal (and which is hosted in countries whose authorities don't care), so they artificially make the list longer by including also legal porn sites, just to show that the measures are "effective".
But the reason doesn't really matter: They are already abusing the law for something which the law does not give them any rights to do. Even if it's just for shows, and even if there's not really a big harm being done, it's still an abuse of the law. The law does not give them permission to censor legal sites to simply give the illusion that "something is being done".
So it's not a question of "can the censorship law be abused by authorities?". They are abusing it already. They are already doing things the law does not give them any permission for.
The exact police official or officials deciding what goes into the censorship list is not divulged publicly. There is no official entity inside the police forces, publicly appointed by the Finnish government, whose task is to estimate and decide what is illegal material by the laws of Finland and should go to the censorship list. The Finnish public does not know who exactly is generating this censorship list. In other words, it's a secret kept by the police and the government.
Wikipedia defines one property of a police state as:
Political control may be exerted by means of a secret police force which operates outside the boundaries normally imposed by a constitutional republic.