What is the likelihood of getting an age waiver to become a Reserve Officer?

If you're trying to direct commission as a lawyer, I'd say your odds are good. Only one way to find out.

The key question is what are you trying to do? If you are trying to become a JAG officer, a direct commission would be the easiest route. In my experience as a ROO in an ROTC program, waiver approval is based a lot on the need for officers. So if you are qualified in every other area and the unit needs JAG officers, there is a decent probability that a commander approves the waiver. If you are looking to commission as an officer into a basic branch which would require ROTC or OCS, that may be different. The best route is to go directly to the source and ask. Here is the website for reserve JAG officer recruiting. They can give you the definite answer. https://www.goarmy.com/jag/jag-reserve-component.html. Good luck.

Chances are you are going to run up the 20 year before 60 barrier. So depending on your age and prior service I guess only you know that.

Now, I say give it a try, keep pushing and find out the regs and who is giving waivers. The USAR is reaching out through all imaginative programs to pull in officer material.

Reach out to higher level USAR commands in your area.

Example: My 1 star general command (not the USAR or higher) was sponsoring a scholarship program for soldiers to complete college and a path toward commission. Now, they were not just giving out LT bars. They were still awarding the commission with the regulations of "Green to Gold". The point to take from this is a ONE STAR was allocating budget funds (I'm sure with higher approval if needed) for scholarships to entice soldiers within his command to become officers in his ranks.

I've literally had an O6 I have no association with (because he probably knew a Sr officer who knew a Sr officer who knew my company had slots) push a memo through my office staff to get my company commander level signature to expedite an OCS packet.

Find the right USAR General Command that is looking for officers anywhere they can find them and then you have a direct line to the waiver authority, or at the very least a general interested in keeping tabs on your packet to see that the right waiver authority moves it forward.