I think that the issue is less clear cut than the OP says even in the UK BUT you do need to think carefully about the requirement AND the impact. Asking for 10

I think that the issue is less clear cut than the OP says even in the UK BUT you do need to think carefully about the requirement AND the impact. Asking for 10 years experience you would need a VERY good reason why that was necessary for the role. Asking for a year or two probably would be unlikely to cause issues especially if the experience could be gained outside of employment (e.g. open source or personal projects). I think you would be at very high risk of problems if you specified something like: "PhD or Masters and 3 year commercial experience or Undergraduate degree and 4 years commercial experience" as you would be basically saying you want someone over 25. On the other hand there might be issues if you specified recent graduates for a Graduate Training scheme as it may be seen to discriminate against older people.