Summary: In general, software patents that deal with technical effects, physical parameters, and improving computer function tend to be favored. By contrast, international 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. Previously, China didn’t allow machine-readable medium type claims, and game patents. 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,). Europe does not allow methods directed “only” to doing business. They also don’t allow patents on computer programs without “technical effect.”
United States: “It’s complicated”
The US rules are still somewhat incoherent. Traditionally (before 2014-2015) US policy was permissive. The written US law is compatible with all types of software patents. 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 still somewhat 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. The USPTO is more likely to reject “Business method” software as being “abstract”. However, software that exhibits technical effects, operates on data pertaining to physical properties, or improves computer function is often OK. It helps if the software uses cameras, AI, or non-standard peripherals. Arguably the US has somewhat borrowed rules from other countries.