The idea of patents goes back to the medieval monarchs who conferred rights and privileges in the form of open letters (latin "litterae patentes") bearing their royal seal. Such patents on procedures to make glass, for instance, were commonly granted on the basis that this skill be taught to others.
Later, democratic governments took the place of monarchs, but the basic idea remained the same: a limited monopoly was granted for a certain invention or process in exchanged for making that invention or process public. That way others could learn from it and further develop new inventions and processes.
The underlying principle of patents and their justification is that they are monopolies which are granted by society for the sake of benefitting society.
Software itself is implemented logic. Consequently, software patents are monopolies granted on implemented logic. It is important to understand that such monopolies are not on the implementation itself, which is covered by Copyright, but on the underlying logic of the implementation.
Therefore, a software patent manifests a monopoly on specific calculation methods, which makes mathematical laws, logical rules and business processes property of companies, effectively disappropriating society of its grown knowledge.
The effects of this can be dramatic. Not only does every program literally embed thousands of ideas that could be subject to software patents: While patents in other fields normally don't reach far outside the field they were granted in, software patents affect all areas and applications of software equally.
Since software itself is increasingly becoming a determining factor, software patents have an incredible reach and more or less cover all areas of economy and society.
Software patents are affecting the electricity industry as much as they affect insurance companies. They harm IT companies like IBM and research institutes like Fraunhofer. They are even bad for health.
For good reason did the European Patent Convention (published 1973) explicitly state that the field of programs for computers, i.e. software, is excluded from patentability.
Software patents are harmful to innovation, economy and society, so they lack justification.
Software patents were seen as a convenient tool by large companies in the United States to defend themselves against competition:
"If people had understood how patents would be granted when most of
today's ideas were invented and had taken out patents, the industry
would be at a complete stand-still today. [...] A future start-up
with no patents of its own will be forced to pay whatever price the
giants choose to impose. That price might be high: Established
companies have an interest in excluding future competitors."
It should be understood that while the price of software patents is paid by all companies, big and small, the big ones can afford paying the price a little longer as they have deeper pockets. Also, they believe that it is worth the price to rid themselves of competition.
Paying the price for the system, companies obviously want their return on investment, which is why the Business Software Alliance (BSA), a lobbying organisation for huge U.S. companies, has been pushing strongly for the adoption of software patents in Europe, without European involvement.
Europe as a region is still gaining on the U.S. in terms of IT industry as it is free from the burden of software patents that the United States imposed on themselves.
The small and medium software companies have made Europe a central player in innovation, while in the U.S., innovative software development is limited to a few monopolists.
Another group that benefits from software patents are patent lawyers, because patent lawyers are needed to apply for a patent, to grant a patent and to contest a patent in court. From their perspective, software patents offer an area of almost unlimited patentability without the need for development or research.
Of course, patent lawyers are also found in the European Patent Office (EPO), which has prepared the ground for the introduction of software patents by granting roughly 30,000 software patents -- acting clearly outside its mandate and disregarding the European Patent Convention from 1973.
Since patent lawyers are also found in many ministries across Europe and not wanting to step on the toes of the EPO, several European politicians are now trying to legitimize these patents by declaring these to be "computer implemented inventions."
That is why the directive in question is called the directive on "patentability of computer implemented inventions."