In general, I am happy to write a letter of recommendation for anyone who has taken a class or done a 3rd/4th-year project with me.

(If you are a PhD student or postdoc going on the academic job market, and I know your work well enough, I'm also happy to write a letter for you; the advice below is intended mainly for undergraduates and you should just send me an email.)

The purpose of this page is for students to get a feel for the process of asking for a letter, and to lay out clearly when I will not be willing to write a letter so that no one feels blind-sided.

As a matter of professional ethics, I will not write letters of recommendation for programs or jobs involving any of the following:

- Policing (including but not limited to predictive policing, development of algorithms that predict recidivism, etc.);
- Military applications, including intelligence;
- Weapons manufacturing;
- Private-sector organisations that rely heavily on insecure employment, poor labour conditions, and/or union-busting (in practice, this means you should do some homework on this before asking for a letter for a job in the tech sector);
- Fossil fuel extraction.

I am very happy to discuss this policy with any student who has questions. Conversations about when and how mathematics should be used are lacking in our community, so in fact I encourage questions and discussion! However, this policy is non-negotiable. Therefore, if it's invoked when I am asked to write a letter, it is not personal.

This policy has been suggested by the Just Mathematics Collective, who are compiling a list of resources for students on making ethical career decisions, available here.

Having understood that, if you need me to write a letter for you, please send me an email (mh17540 @ bristol.ac.uk)! This should detail when you need the letter, what it is for, why the opportunity interests you, and why I am the right person to write the letter. Please include clear instructions for submitting the letter once it's written. If possible, please include some sort of resume/CV --- it doesn't have to be official --- detailing your past experiences relevant to the application. All of that will help me to write the most effective letter I can.

Finally, my colleagues and I all write many such letters each year. It's a very important part of our job, and we want to do it as well as possible. So, when requesting letters from any of us, please give as much advance notice as possible, ideally something more than one month.