What is the role of a lawyer in a Mergers and Acquisitions transaction?

I would like to study law and this is a topic which I will have to present at school. Basically, I will have to talk about Mergers and Acquisitions but I find it hard to relate it to law. My presentation sounds more like a business talk. So what should I include in it and what exactly is the role of a lawyer dealing with Mergers and Acquisitions?

Thanks!

M&A is a specialized area of law dealing with not only the contracts, but also the financing, securities, real estate, corporate control and voting rights, technology licenses, and so forth. There may well be different laws that apply to different parts of the company, or its assets, so you may need a team of attorneys in more than one state. If done improperly, the shareholders of either company can sue the board of directors and the attorneys and accountants who set it all up.

Lawyers are the ones writing the contract. Contracts have to respect the law, plus the lawyer is more qualified to determine what rights and obligations to put in a contract to make it as advantageous as possible.