I decided to leave research after becoming dissatisfied as a postdoc in an academic cell biology department. I felt I wasn't developing as a scientist, but was instead being used as cheap labor. I became very frustrated at the lack of job prospects and the low pay--things I was willing to tolerate only in return for advancing as a scientist.
Because I wanted to stay in touch with science, I began to look for another career in which I could use my background. Patent law seemed to give me the best opportunity to keep in touch with real science because every day patent lawyers deal with the latest scientific innovations.
Once I had decided on a career in patent law, I considered a job as a patent agent. Patent agents are licensed to prepare and process patents, but they do not have a law degree. Although this would have been an easier and quicker path, I instead decided to bite the bullet and go to law school. At the time, I had few family or other responsibilities, and I figured I should jump in all the way while I had the chance because it might be harder later in life.
I decided to go to law school at the Georgetown University Law Center  full time, although the decision tormented me throughout my 3 years. After working part time in a firm for a while, I started to feel a lot of pressure to go to school at night and work full time. Admittedly, the financial benefits and additional experience I could gain by working full time were very attractive. Some firms even help with tuition and pay large salaries to such "student associates." In exchange, though, student associates have a very hard road--completing law school by taking night classes takes 4 years (an extra year!), and there is little time for anything except school and work. Also, because they are regular salaried employees, work must come first. There may not be enough time to explore opportunities at school, such as other areas of law. Of course, working and going to school is only an option in cities that have night law schools as well as patent law firms that practice in your technology area.
Eventually I chose a compromise of going to school full time and working part time throughout almost all of my 3 years. This compromise was a little less demanding than working full time (I was paid hourly, so when exams came around, I could choose not to work at all) and it allowed me to concentrate on some courses that exposed me to other issues, such as transgenic agriculture, biomedical ethics, even biological weapons and international law. I still don't know if I made the right choice. I am certainly lagging behind those who worked full time in terms of experience and seniority in the firm, but hopefully that difference will become less apparent with time.
Within patent law, there are some choices as to the type of practice you can have. For example, you can choose to either "prosecute" or "litigate." Prosecutors write and process patent applications to be submitted to the Patent and Trademark Office, which grants patents to inventors. Litigators, on the other hand, go to court to defend or attack the validity of an existing patent. Which path should you take? Well, litigation is usually a faster paced lifestyle than prosecution, and often involves considerable travel. A lot of lawyers like the showmanship and argument of the courtroom (or preparation for it--few cases actually go to trial). Although prosecution may sound less exciting, lawyers who choose patent prosecution get exposure to more hot-off-the-bench science, because they are writing patent applications for scientific inventions that are still confidential. Prosecutors also read scientific papers to determine if the invention has been described before in the literature. The schedule of prosecution is somewhat more predictable than litigation, so it can allow for a more relaxed lifestyle. Large firms often do both prosecution and litigation, so young lawyers can try both to see which fits them the best at these firms.
I've experienced many ups and downs changing from science to patent law. One of the biggest positives is the increased salary. As a graduate student and postdoc, low wages were an expected and almost perverse badge of honor. But high salaries come at a cost. While I thought no one could work harder than my colleagues and I did as graduate students and postdocs, young lawyers work very hard. Just as in science, there are many hours of boring tedious work. In law, though, it is all mental work (reading and writing) not the hands-on kind of routine labor I did in science. There are also different pressures in law. As a researcher, most of my pressures were to get good results, which mostly affected only my own career. In contrast, a young associate in a law firm works for the partners and clients. I tend to think of the pressures I have now as more "in your face" pressures than those I had in the lab.
All in all, I am very pleased with the change. I am no longer in an environment of constant depression and pessimism about the future. There are many options open to people with both law and science degrees. And once in law, there is a great deal of flexibility--unlike scientists, lawyers usually do not have as much time and emotional investment in a career-long project, so if a certain situation is not right, lawyers can typically change jobs more easily than researchers. I also really enjoyed law school because of the new intellectual challenges. I had become very burnt out in my field of science. Lawyers are generalists, and there is always something new and completely different to learn. Finally, while law is still new to me, I am very comfortable with the level of science I am called upon to know. I finally feel that I have hit the right balance between my love for science and a way to apply it.