I have personal experience defending against a stalker. Questions were asked down-thread about the effectiveness of restraining orders, so I'm posting in response. I got away, and I find the slight chance that this helps someone else compelling. Also, I can't really talk about this in real life, so I wish other people could know that it can happen, and how it works.

TLDR answer is: To defend against a stalker you will likely need legal advice and representation.

This is distasteful and expensive, and judgment is required to decide when to take that step. I am not a litigious person, and generally prefer to avoid conflict, or negotiate reasonable solutions. A stalker will take advantage of this. Stalkers (at least mine) operate by asserting control gradually, and retaliating against your attempts at self defense in a tit-for-tat fashion.

I think it likely that if you have even considered seeking legal redress, it's probably already time to hire an attorney. The cost and risk of civil cases or lawsuits is generally much smaller then the cost/risk of potentially getting involved in a criminal case later, so if you can solve the problem in civil court, it is highly desirable to do so.

The police may arrest and charge one (or both) of you if they respond to an in progress assault. However, they will not want to evaluate contradictory factual claims made by you and the stalker about things that happened while they weren't there. When you ask for help, they will probably encourage you to obtain a restraining order, which makes the problem someone else's job for now, and sets at least a low bar for complainants, before the police have to get involved.

Your legal position in the future will be constrained by early decisions and statements that you make. The article describes this question from a police officer: “'Were you ever afraid for your life?' he asked, still apparently on my side."

In my state, fear of one's life or safety was a legal requirement for obtaining an ex parte domestic violence civil restraining order. Think very carefully in advance about how to answer questions like this and don't ever lie to anyone or change your story. Lawyers are required to tell a judge if you do, and you will also need to protect your reputation with people you know against claims made by the stalker. Your only advantage over the stalker is truthfulness and consistency.

A civil restraining (or "protective") order is issued by a civil court which orders one party to stay away from another, possibly along with other provisions . Ex parte means "without the other party's presence." Some states (including mine at the time) allow such an order to be issued without an adversarial hearing. You obtain this by: going to court clerks office and submitting the paperwork they give you. Soon, (because this is presumed to be an emergency) you are given a short hearing in which you must explain why you are afraid for your life, and what's happed so far. If the judge grants the order, the respondent will be served a paper copy of the order by an officer, who will explain to the respondent that it's a crime to approach or bother you while the order is in force. These orders are short (mine was 21 days) because the respondent is not allowed an advance adversarial hearing.

After being served, my stalker retaliated by obtained an ex parte restraining order against me. I have come to understand that this is not uncommon in states where reciprocal orders are allowed. Eventually, after some stalling, I was granted a hearing and that order was dismissed at my request. Ultimately, after many further hearings over the course of about a year, I was granted a long term civil restraining order. During the litigation I dropped my college courses, resigned from my internship, and finally transfered to a university in another town. I did this partly because it was advised by my attorney, but mainly because I wanted to move on with my life.

It was also my experience that other people tended to trivialize the problem. It was hard for some people to understand that simply ignoring the stalker would not make it possible for me to attend work, or class, or use public spaces. My stalker would wait for me outside of my school and workplace, hold the doors shut, and threaten to report an assault if I tried to get in. They would also follow me in public or into businesses and create disruptions by yelling, making false reports to police or security, or other authority figures. The goal seemed to be to deny access to a space and/or provoke a physical altercation so I could be charged with assault.

I got out of this for a few thousand in attorney fees (plus a year of my life), and was never injured or charged with a crime. If I had not hired an attorney, I think there is a chance I would have been injured, killed or imprisoned. There were some peculiar features of my case that probably make it exceptional, so I'm not sure how well my advice generalizes, but this is it: Don't engage with the legal system without a lawyer, and don't wait to start defending yourself.