The person would have to pass his boards again. It is a test that doctors have to take every 10 years to be board certified.

^^ So basically, the degree itself never expires it’s just the qualifications and such that go with it that need to be retaken so they qualify again.
BUT
Some fields may require (or ask) you go back to school for some classes for refreshers, such as some IT fields. but it wouldn’t be because your degree ‘expired’ just that things change so fast you need to be caught up. Most of the foundations stay the same.

His medical degree would not expire, but his license to practice medicine would.

I was told from an university calendar that science and computer science courses expire after 5 years.

In America, the degree never expires. To be able to practice medicine you need a state license. If the person let the license lapse they would need to get another. In America just moving to another state you usually need to get another license—go through the testing process again and whatever background checks that state has. If you work for the military or some sort of federal instillation you can be licensed by any state I think.

Board certification is different than licensing if I understand it correctly, we might need caravanfan. Board certified is when a doctor has demonstrated a mastery in a particular part of medicine.

Side note: Once a doctor, it’s proper to address the person as Dr. even if s/he retired. It’s like how we still call former presidents Pres. Lastname. Once you earn the degree or position the title stays with you.

@RedDeerGuy1 What you may be reading is that courses one took years ago in STEM, if the person has not completed their degree, are not considered valid for credit toward a current degree because the disciplines have changed so much. But if one has already obtained the degree, they may need to get relicensed in certain fields but the degree is still valid.

Yes, if he was up-to-date on his CE and license requirements.

Degrees do not expire! Licenses expire and there is always a chance that within a 20 year period requirements can change.