Young offenders and accused aged 16 and 17 can no longer be identified in Scottish criminal cases.
The age at which charged youths can be named in the media was raised from 16 to 18 last week in a move to bring Scotland into line with the UK and the rest of Europe.
Previously, anyone accused of a crime lost their anonymity at 16 as they were considered adults in Scots law.
The change is part of the Victims and Witnesses (Scotland) Act 2014, and applies to defendants and evidence.
Although the change was approved last year, it did not come into effect this week and caught many journalists and lawyers by surprise. The Scottish government announced the implementation date in May, but did not issue any reminders after that.
Freelance journalist Campell Thomas, who covers Scottish courts for Hotwire News, said: 'I don't know anyone who was expecting this to take effect when it did. I had to check with the courts office before filing copy.
'But some government press releases get intercepted as spam, so many editors were unaware of the changes.'