I've never seen him sue to collect. I advise my clients to ignore him and I write him a letter telling him to stop contacting my client, which he must honor under the ethics rules. Not paying will not lead to criminal charges.
I am a former federal and State prosecutor and have been doing criminal defense work for over 16 years. I was named to the Super Lawyers list as one of the top attorneys in New York for 2012 and 2013. No more than 5 percent of the lawyers in the state are selected by Super Lawyers. Martindale-Hubbell has given me its highest rating - AV Preeminent - in the areas of Criminal Law, Personal Injury, and Litigation. According to Martindale-Hubbell”AV Preeminent is a significant rating accomplishment - a testament to the fact that a lawyer's peers rank him or her at the highest level of professional excellence." Fewer than 8% of attorneys achieve an AV Preeminent rating. I also have the highest ranking – “superb” – on Avvo. Feel free to check out my web site and contact me. The above answer, and any follow up comments or emails is for informational purposes only and not meant as legal advice.