I am a results-oriented, energetic advocate for my clients. I am passionate about representing my clients. As most cases come from word-of-mouth referrals, I am proud of my reputation built one client at a time. Most clients are faced with a difficult challenge in a critical part of their lives: their jobs and careers. I am competitive and look forward to taking the fight to the employer to redress unfair and illegal actions. I align our firm's fee arrangement with the client's desired outcome so that there is an identity of interest in the result sought. My success is defined by each client obtaining the desired outcome as a consequence of my effective counsel. Most of all, I love what I do, and that is helping people and seeking fair results for clients who deserve better treatment from their employers.
5
Practice Areas
37 years | 5,000 cases
37 years | 200 cases
37 years | 400 cases
37 years | 500 cases
33%-40%
State: New Jersey
Acquired: 1989
No misconduct found
State: New York
Acquired: 1989
No misconduct found
State: District of Columbia
Acquired: 1991
No misconduct found
178 Client Reviews
Showing 166 - 170 of 178 reviews
Posted by anonymous | August 28, 2020 | Hired Attorney
No Nonsense Advocate
Jonathan provided the support I needed through a tough time. He was direct and fearless when advocating for my rights with a former employer. He takes a no-nonsense approach to get things done and is well-balanced by a team that fights equally as hard with care and compassion. He gave me practical...
Posted by anonymous | October 14, 2019
Employment Dispute
I contacted Jonathan based on a friend's recommendation. He responded to my emails and phone calls right away. He was extremely direct and and knowledgeable. He didn't think I had much of a case but did give me good advise. I would contact him again in the future if I find myself in another empl...
Posted by anonymous | September 25, 2020
Unhelpful for a consultation
I found Mr. Slack through his website, which states he offers free consultations and gave a brief overview of my claim. Mr. Slack then responded asking, if my pay wasn't reduced "what is this claim for?" and "How would I be compensated if there is no money involved?" While both these concerns are com...
This young attorney did not accept the reality that without ascertainable damages, a matter is best initially handled through opening a dialogue with a supervisor or through Human Resources. Not all matters require outside counsel's involvement. Practice note: Always check spelling before hitting the send button.
Posted by anonymous | April 11, 2024 | Hired Attorney
One of the WORST in the business
The other one star reviews are 100% accurate. He is a vile human being and is fake nice at first only to turn on you once he thinks your case isn’t worth millions. He pawns you off on junior staffers who are just as incompetent. He expects clients to write their own complaints! I’m not a lawyer! Mess...
Posted by anonymous | December 02, 2022 | Hired Attorney
Didn't handle case properly
Didn't handle case properly. He totally misjudged the situation, which resulted in very poor compensation from an employment termination case.
Some clients have an unrealistic sense of what their case is worth. With a contingency fee arrangement, our interests are aligned with the client's interests. We always try to zealously represent a client to maximize the outcome and achieve the client's goals.
"Jonathan is one of the most professional, effective, and direct attorneys I have ever met. His knowledge of labor and employment law is vast and very respected. You can't go wrong having him on your team."
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2025
Super Lawyer, Super Lawyers
2024
Super Lawyer, Super Lawyers
2024
Client's Choice, Avvo
2023
Super Lawyer, Super Lawyers
2017
Super Lawyer, Super Lawyers
1986
Dewey Scholarship, Dewey Scholarship
1989 - Present
Partner, Sack & Sack, LLP
1989 - Present
New York State Bar Association
1989
JD - Juris Doctor
1986
BA - Bachelor of Arts
English