Is this racist and unfair?

My brother is in year 9 and has trouble issues with the school (they always seem to be picking on him) he is in the wrong don't get me wrong but, his friends are the main culprits, but were he is with them he gets named but he always takes the wrath for their crimes, and his friends also admit to what they have done, but my brother still gets the main punishment. My question is this, is calling a polish boy a immigrant, racist? As my brother is getting done for thus, and again he is getting all of the blame from the school, the main culprit is another polish boy but he is actually not getting done for anything. My mum is thinking about getting a solicitor in for the next meeting as this could destroy his whole life for an inappropriate result.