Summary: In general, software patents that deal with technical effects, physical parameters, and improving computer function tend to be favored. By contrast, software patents focused on business methods tend to be disfavored.
China: Before April 2017, China restricted software patents to methods that solve technical problems, control internal or external processes according to the laws of nature, and produce technical effects in accordance with the laws of nature. Machine readable medium type claims, and game patents, were not allowed. However these guidelines are now somewhat more expansive. For example, business methods that also have a technical aspect may now also be eligible for patent protection.
Europe: Software patents should have a “technical effect” (e.g. controlling industrial aspects, improvements in computer technology, data pertains to physical properties,). Pure methods directed “only” to doing business and computer programs without “technical effect” are not allowed.
United States: The rules are presently incoherent. Traditionally (before 2014-2015) US policy was permissive. Indeed the present written (i.e. statutory) US legal standard is that all types of software patents are permitted. However the latest judicial rulings and USPTO policies are that at least some software patents may represent “abstract ideas” run on “generic computers” that are not patentable unless there is “something more”. Unfortunately the terms “abstract”, “generic computer” and “something more” are effectively undefined (and thus can vary according to the whims of the judge or patent examiner at hand).
How will US software patent rules evolve in the future? This is a bit like reading tea leaves, but the latest US software patent decisions appear to be trending more towards a Chinese or European-like approach. On average, “Business method” software is increasingly being rejected as being “abstract”. However software that exhibits technical effects, operates on data pertaining to physical properties, or improves computer function is often accepted on the basis that it is not “abstract”, not run on “generic computers” or contains “something more”. Arguably the US, presently lacking coherent rules, may be at least temporarily filling the void by borrowing rules from other countries. The constitutionality of this approach remains to be determined.