Some parts of the original text in Spanish are not very clear, not because they are not clearly written but because the reader cannot know some facts which the Centelles brothers describe very quickly. For example, the original Spanish contains the word "presupuesto", which is most often used as "budget", but it might also mean "assumption". I translated it as "sums", but I really cannot be sure what it really means.
In the interest of knowing what was going on, I followed several links and I think I understand what the matter is.
The plaintiffs are Sergi and Octavi Centelles, the sons of the late Catalonian photographer Agustí Centelles. This was a famous war photographer and some of his work can be seen here:
They are claiming that the Spanish Watchtower used a picture taken by their late father in a way that violates Spanish copyright laws.
According to Octavi Centelles (http://octavicentelles.blogspot.com/), copyright laws were violated: no authorization was requested to use the picture; the picture was manipulated to omit some of its contents (the arm at the bottom); no mention was made of the author, and it was reproduced in 16 million magazines without the payment of royalties, and this at a time when the Watchtower magazine was indeed sold for a price. In Spain, the price was thirty pesetas, "half of the price of La Vanguardia (http://www.lavanguardia.com/), a journal of countrywide distribution".
The original picture:
The basis of the claim:
Octavi Centelles also claims that "The Watchtower paradise is that expensive that it costed 50% of the sale price of a journal which contained six times more pages and contents" (¡que caro es el paraiso de la Watch Tower que valía el 50% de un periódico con seis veces más paginación y contenidos!). In my opinion, this is meant to say that the sale price was not negligible.
Here is the link that Octavi Centelles gives so people can check what the sale price of La Vanguardia was at the time:
http://hemeroteca.lavanguardia.com/preview/1986/02/01/pagina-1/32870921/pdf.html
So, if I understand this correctly, in brief, the Centelles are claiming that the Watchtower made illegal use of a picture taken by their father, and that the Watchtower made a profit out of that publication.
The Centelles brothers want 90,000 euros for the publication (http://www.lavanguardia.com/vida/20110424/54144627896/los-hijos-de-centelles-reclaman-90-000-euros-a-una-revista-religiosa-por-publicar-una-foto.html). This is their case against the Spanish Watchtower. They are also thinking to file similar claims in "other countries, such as the United States, Brazil and Japan", according to the article I'm quoting above.
Apparently the Watchtower refused to settle the dispute:
Es una lástima que por la prepotencia y las malas formas de los dirigentes de los Testigos de Jehová, nos llegaron a mandar una carta, desde Madrid, con el papel membre de la confesión, en inglés y sin firmar. Lamentablemente el caso ha acabado en el Juzgado Mercantil núm. 3 de Madrid, donde se verá la vista previa el próximo 12 de Mayo.
!It's a pity that the arrogance and bad manners of the leaders of the Jehovah's Witness went as far as sending us a letter in the official letterhead of this persuasion, sent from Madrid, in English and without a signature. Most regrettably the case ended up in the Third Court of Commercial Concerns of Madrid, where the first hearing will be held on May 12".
The Centelles also claim that this is not the only time the Watchtower has made such use of pictures:
This is an image taken from a German magazine, Stern.
Now, the picture involved in the claim is very famous in itself. It is called the "Mater dolorossa", or "Mother grieving", and it shows the wife of the late Gabriel Pernau, mourning his death (http://testigoscristianosdejehova.blogspot.com/2009/02/la-sociedad-watchtower-y-sus-maestrias.html).
The picture was taken to document the bombing of the Liceu Escolar in the city of Lleida. It was bombed by the Italian aviation, while Mussolini was in power, in support of the Nationalist side in the Spanish Civil War.
The Liceu Escolar was an anarchist school that followed the principles of the Escola Moderna. It was "intended to educate the working-classes from a secular, liberal, class-conscious perspective.". So the Italians destroyed what you could call the nursey of "red" ideas.
The casualties were 700 hundred, 48 of them teachers and several children. There is now a sculpture in the figure of a man lying on the floor, in memory of the victims.
The Escola Moderna was initiated by Catalonian Francesc Ferrer i Guardia and its principles were adopted even in the United States.
Liceu Escolar: https://secure.wikimedia.org/wikipedia/en/wiki/Liceu_Escolar_de_Lleida
Escola Moderna: https://secure.wikimedia.org/wikipedia/en/wiki/Modern_School_%28United_States%29
In Catalonian: https://secure.wikimedia.org/wikipedia/ca/wiki/Escola_Moderna
In Spanish: https://secure.wikimedia.org/wikipedia/es/wiki/Escuela_Moderna
Apparently the government of Spain bought the work of Agustí Centelles (Spanish only, sorry) http://www.elmundo.es/elmundo/2009/11/29/cultura/1259492512.html. I don't know what this means for the claim.
As to Snoozy's question, yes, that seems to be what the Centelles are saying, that the Watchtower didn't want their publications resold, while they do nothing to stop eBay or todocoleccion from reselling.