When you are acting in loco parentis, you can't wait for the law to tell you that it's OK to do something necessary to ensure pupils are safe. Most schools use their common sense and search when they think it's appropriate.
Pupils have to understand that if suspicions are raised, they will be searched. They have to know they are answerable for their actions.
Schools that aren't already carrying out searches shouldn't be afraid to start. Alcohol and drugs are problems that have to be dealt with. Mobile phones are more of an issue for us because they can be used to organise gangs and fights.
Searches have to be part of a wider approach to tackling bad behaviour. We do a lot of work on conflict resolution and developing pupils' emotional intelligence. You need to show pupils a different way of behaving.
An atmosphere needs to be created where pupils feel comfortable telling staff when someone is carrying something they shouldn't. It's not snitching, it's protecting everyone from danger. Staff need to be good at listening, picking up on rumours around the school and acting.
And, of course, parents have got to take responsibility as well. Everyone, including the police and youth services, have to work together to tackle poor behaviour both inside and outside the school gates.