What is best practice for putting an HR person on a written performance plan?

Why? Just as you said, the person responsible for corporate personnel performance who doesn't perform should being invites to that exit interview talked
about in the other thread.

We are taking about an extended period of non-performance here, and I assume the employee has been counseled

There's multiple resources out there for developing a performance action/improvement plan. A plan can be as simple as dates and times of incidents with a time frame for improvement. The real question to me is if anyone has had verbal conversations with this person has it been documented? Otherwise you're starting at step 1, which means place the person on an action plan, as you mention (I am sure you can Google Action Plans or Performance Improvement Plans and find several) listing specific issues and a time line for improvement. If you give the person 30 days to get it together then there should be a weekly meeting to openly discuss progress so that everyone is on the same page. Senior leadership has done the person and the company unjust by allowing the behavior to continue without repercussion. If you are in a right to work to work state and you feel that it's better to terminate now; then you are free to do so; just plan to pay unemployment unless you can document specific instances of work related misconduct.

Unfortunately, if the under performance has not been documented in the past, you need to start the process now. The key job responsibilities and goals should be documented, the gaps explained, a timeline established and an end date for improvement agreed. The initial meeting will take some time, but the investment will protect you and the company legally and ethically. I agree that weekly meetings are a minimum best practice, but if the employee "acts out" between meetings, you will need to confront immediately. Document every discussion.

This brings up a question: Has anyone ever seen a performance improvement plan actually work?

I've used them. And, I've been subjected to them myself - in retaliation for doing what I was told to do by my boss the CFO.

I've never seen them work out well in the long run. They've usually only delayed the inevitable. Generally, they were used by management as a way to "lawsuit proof" a termination. And, in the few cases I can remember where the employee survived the "progrom", they created a sense of ill will and damaged morale for everyone. The "counseled" employee eventually left anyway even after making it through.

CA is an "at will" state. According to legal counsel to whom I've spoken about this, one of the ways to throw "at will" out the window is to have an institutionalized performance improvement plan. You will be considered contractually obligated to it and to have chosen to not be "at will" when you adopt one.

But. I'm not an attorney so, what do I know? ;-)

As an employer and an employee, I prefer to deal with such matters swiftly and head on. It's easier on all concerned to cut one's losses and move on. Employment is not a lifetime commitment or contract. For either side. It's just a temporary station in life for both.

As to lawsuits, there is really no stopping them. Be sure to stay away from protected class and civil rights issues and, you are as protected as you can be.

Earlier in my career I worked for a company that was very rigid about the process. Three documented warnings before a recommendation to terminate, which was approved by Corporate. The process required one full year. Over the years it became clear that this approach was the safest. Do not depend on any "at will" status. Document, document, document. I have never seen a performance plan truly work at turning around an employee. But I have administered the process through the full year to termination. It is very disruptive and expensive to the company.

Based on the comments and information shared, I would add that documented performance issues do not necessarily have to be "PIP" forms etc. If the incompetence, negligence, or errors have been persistent, and management was consistent in bringing these issues to the HR employee's attention, then a meeting recapping the timeline of events (e.g. outlook scheduled meetings, emails, phone calls, etc) could result in termination that will minimize legal risks. Get your timeline and facts together, run it by an employment attorney, and resolve the matter so you could get back to business. Before hiring the next HR person, get to root cause of the skills and competencies there were not present with the incumbent, and realign the job requirements. One year for a wrong hire is a long time.

Putting an HR person on a performance plan shouldn’t be different than an employee who works in a different discipline, but you may anticipate that your performance plan will be under greater scrutiny, so be sure you have your ducks in a row. The principles of a good written performance plan are to document; I can’t stress this enough. Our friends in employment law like to say that if it’s not in writing, it’s like it never happened. Your HR person knows this, and should respect and appreciate that you’ve had to take the step of putting a correction in writing. “In writing” can be on paper, but email is also acceptable. If this is a first infraction or first time you’ve felt the need to document an ongoing issue, verbally discuss the matter with the employee, then follow up with an email to document your conversation.

For a more egregious issue, or something you’ve had to repeatedly discuss with your HR person, it’s time to write out a longer performance improvement plan. Get some help from another trusted leader at your company, or even legal counsel if the matter is delicate. You should write the first draft, and follow these principles: Be Specific, Clearly articulate what the person did, or didn’t do, that is the subject of this counseling. Explain the consequences the action had, and what will happen next if the issue doesn’t change. An example is “Ron, when you didn’t deliver the turnover report by the 31st, the CFO didn’t have what he needed to present to the BOD, thereby jeopardizing our departments good reputation with the decision makers at our company. I expect all future deadlines to be met, or that you will advise me early if you’re not going to be able to keep a commitment that you made. If this doesn’t resolve itself, you could be subjected to further disciplinary action, up to and including termination of employment.” That last sentence feels too harsh to some, but if the offence is serious enough to lead to her termination if it occurs again, then you need to be crystal clear that a termination could happen.