Hey there,
Generally for questions like these, you could structure your essay according to broad points eg. search and seizure, gathering evidence and arrest. But if you wanted to show more knowledge you could incorporate issues such as terrorism, sexual offenders or sniffer dogs into your broader points. So you could incorporate sniffer dogs into search and seizure, terrorism into gathering evidence and sexual offenders into arrest - but only do this if you have adequate LCMIDO (legislation, cases, media, (forgot what 'I' stands for), documents and opinion). An example of this could be talking about how s230/231 of LEPRA (2002) allows for police to use reasonable force.
In my opinion, I don't think having a summary paragraph on the central legislation is a good idea because usually 1 to 2 sentences outlining the legislation relating to your broad point after your topic sentence of course, is enough to begin your argument. Every crime essay follows the same structure, with the introduction, 3-4 broad points and the conclusion, though your points may be more specific depending on the question. In terms of writing crime essays, the amount of paragraphs does depend on the question, so do whatever you think is appropriate - whether that's 4 paragraphs, 3 paragraphs and so forth.
Hope this helps
- avocadinq