We get asked the following question regularly: “I would like to deploy Koha in my library, can I do a tender offer explicitely quoting this product?” (you can replace Koha by any Open Source Software)
In France, the legislation is clear (décision N°350431 [fr]), it is perfectly legal.
In Italy, it is perfectly legal too, since a law validated in 2009 by the Consiglio Regionale del Pietmonte: Norme in materia di pluralismo informatico [it] and confirmed by the corte constituzionale1.
These laws must exist in many countries nowadays, if you have some information about your country, do not hesitate to tell us more about it in the comments below.
Here is in plain english why you have the right to create a tender offer explicitely quoting one product (at least in France and Italy):
Tender offers created for an Open Source Software are not supplies tender offers, but services tender offers. The library can freely download and use the software prior the tender offer. Thus, the library is looking for a service supplier to install, set up, eventually adapt the software, train the librarians and provide some support and maintenance.
Any supplier can, legaly and without constraints, offer its services. So, by definition, there is no rupture in equality for the suppliers, anybody can answer to the tender offer. Therefore, it is legal.
End of the argument.
Conclusion: if you want to make a service tender offer and choose an Open Source Software, do it, you are perfectely right. And if you choose Koha, Bokeh, Omeka, Piwik, or Coral you will have an answer from BibLibre, and in all likelihood from other suppliers, we are not the only one providing services on these software (even if we are the best 😉 ).