The Statutory Exclusion
Most people in intellectual property and many in information technology know that art 52 (2) of the European Patent Convention and s.1 (2) of the Patents Act 1977 exclude from patentability:
(a) discoveries, scientific theories and mathematical methods;
(b) aesthetic creations;
(c) schemes, rules and methods for performing mental acts, playing games or doing business, and programs for computers;
(d) presentations of information.
However, the exclusion is not total. Art 52 (3) and corresponding words in the Patents Act 1977 provide that these provisions "shall exclude the patentability of the subject-matter or activities referred to therein only to the extent to which a European patent application or European patent relates to such subject‑matter or activities as such." It has also been noted many times that there is no corresponding exclusion in the patents legislation of the United States, Japan, China or other leading industrial nations.
Effect of the Exclusion
In practice, the "as such" provisions have enabled many patents to be granted for software implemented inventions both by the European Patent Office and the Intellectual Property Office. As Judge Birss QC explained in Halliburton Energy Services at paragraph 
"at the heart of the law is the consistent principle that an inventor must make a contribution to the art (that is to say the invention must be new and not obvious) and that contribution must be technical in nature (susceptible of industrial application and not within one of the areas excluded by Art 52(2))."
He added that he took that observation from Mr Justice Kitchin in Re Crawford's Application  RPC 11 which was decided just before Aerotel and in his lordship's view it was still good law.
In deciding whether a claim is "technical in nature" and "not one within the seas excluded by art 52 (2)" Lord Justice Jacob proposed the following 4-stage approach:
- Properly construe the claim
- Identify the actual contribution
- Ask whether it falls solely within the excluded subject matter, and
- Check whether the contribution is actually technical in nature.
Judge Birss added at paragraph  that "an invention which makes a contribution to the art which is technical in nature (to echo Kitchin J's words in Crawford) is patentable even if it is implemented entirely on a computer and even if the way it works is entirely as a result of a computer program operating on that computer." It is necessary to consider "what task it is that the program (or the programmed computer) actually performs. A computer programmed to perform a task which makes a contribution to the art which is technical in nature, is a patentable invention and may be claimed as such. In those circumstances the patentee is perfectly entitled to claim the computer program itself. If the task the system performs itself falls within the excluded matter and there is no more to it, then the invention is not patentable. Mr. Justice Floyd endorsed Judge Birss QC's approach at paragraph  of his judgment in Re Protecting Kids the World Over.
Scope of the Exceptions
Lord Justice Jacob's approach does not dispose of all difficulties. For instance, in Halliburton Energy Judge Birss QC had to decide between a wide interpretation of the words "schemes, rules and methods for performing mental acts" or a narrow one. The wide interpretation excludes "schemes, rules and methods for performing mental acts" that can be carried out mentally regardless of whether they are carried out in that way. The narrow interpretation catches only those schemes, rules and methods that are actually carried out mentally. Having considered the authorities, the judge concluded that the mental act exclusion is to be construed narrowly.
in Re Protecting Kids the World Over the hearing officer had held that a claim for
"A system for monitoring electronic communications comprising:
- a data communications analysis engine for packet sniffing and assembling packets for further analysis of their content;
- apparatus as claimed in any one of claims 20 to 32 for providing an aggregate alert level;
- a security warning algorithm adapted to provide at least one of a number of alert notifications to users based on predetermined user settings in response to the raising of the aggregate alert level;
- a request and response engine for sending a notification request to an administrator/user advising the aggregate alert level, receiving a response from the administrator/user comprising one of a plurality of actions to be taken wherein the actions include one of alerting a user in an electronic communication, terminating the electronic communication and shutting down the user equipment;
- a system log engine for recording and categorising communications data, actions taken and states within the system."
was not patentable because it related to a computer program and to a method of performing a mental act as such. The applicant appealed. Shortly before the hearing of the appeal Judge Birss QC's judgment in Halliburton Energy was published whereupon the Comptroller indicated that he relied solely upon the computer program exception.
The Comptroller's counsel argued that the claim was nothing more than a computer program as such. She submitted that all the claim does is to inform the user or administrator of the result of the data analysis performed by the computer program and that was not a technical process. The judge did not accept that argument. The invention sent a message to the user or administrator's mobile or other remote terminal that the system had found and was evaluating potentially undesirable and that was qualitatively different from a system that merely displayed the result of the processing on a screen. It amounted to an improved monitoring system which was an advance on the prior art.
Both of these cases are important but I think Halliburton Energy is the one most likely to be cited. Judge Birss QC's analysis of art 52 (2) and (3) and the authorities should make it considerably easier to get computer implemented inventions past the examiner. With the benefit of hindsight his elegant reconciliation of Mr Justice Pumfrey's decision in Halliburton v Smith  Info TLR 323,  EWHC 1623 (Pat),  RPC 2 with later decisions seems obvious. Perhaps European industry is not at such a disadvantage to competitors in countries without the equivalent of art 52 (2) after all.