Licensing Status

3rd party data:

ICD-9 public domain

US provides an MS Access MDB file: https://www.cms.gov/MinimumDataSets20/Downloads/ICD-9CodeDatabase.zip

ICD-10 typically requires within-country status as a 'vendor'

distributed within-country: http://www.nhsia.nhs.uk/clinicalcoding/pages/licensing.asp#icd10

LOINC free to use, but restricts modification (however it is nothing GNUmed needs to modify)

license: http://www.loinc.org/license
Debian packaging requires a separate LOINC package for "non-free".

Australian request and reporting codes http://www.austpath.uow.edu.au/index.cgi
Per Tim C: the former (request codes) is unsatisfactory, and the latter (reporting codes) is just vague with respect to the modifications that have been made to LOINC for Australian use. Worth contacting Michael Legge and ask him to clarify/resolve the licensing in a manner which is suitable for open source software.

References

various clinical/social coding & classification at http://www.p-jones.demon.co.uk/infselct.htm
"free software" is characterized at http://www.gnu.org/philosophy/free-sw.html