If a nonprofit organization is unionized, may they have volunteers as part of a collaborative effort with another organization for a service that is not currently provided? For example, could they collaborate witha volunteer organization for an outreach service that is not currently provided.
This is a very good question, since the use of volunteers to supplement or replace work typically performed by union employees can most definitely be a violation of a collective bargaining agreement.
In one case from 1981, a school district on an "austerity budget" used volunteers to set up (and then clean up) district facilities for student sports--a task typically performed by custodial workers under a collective bargaining agreement ("CBA"). An arbitrator found that the district's use of volunteers to perform the unionized workers' tasks violated the CBA, and the workers were owed pay for the work they should have had the opportunity to perform.
That said, schools, libraries and not-for-profits with unions routinely use volunteers for all sorts of things; clearly, not all use of volunteers risks violation of a CBA. So, my plain answer to this question is: "yes, if the library is careful."
The rest of this reply sets out what I mean by "careful."
First, any not-for-profit has to exercise caution when using volunteers, because (as the member's question points out) there can be concerns that some use of volunteers violates the labor law.
The NY Department of Labor has really good basic guidance on this at https://dol.ny.gov/system/files/documents/2021/03/p726.pdf
In relevant part, that guidance says:
Unpaid volunteers [at an NFP] may not:
• Replace or augment paid staff to do the work of paid staff
• Do anything but tasks traditionally reserved for volunteers
• Be required to work certain hours
• Be required to perform duties involuntarily
• Be under any contract to hire by any other person or business express or implied
• Be paid for their services (except reimbursement for expenses)
Considering this guidance, when I work with libraries and other not-for-profit organizations who are considering using volunteers (no matter what the work for the volunteers will be, and whether or not there is a union), I advise that the organization have a volunteer policy.
The volunteer policy should cover all the concerns raised in the bullets above, as well as address risk factors such as placement letters confirming the terms of volunteer service, safety, insurance, and when a library using volunteers will conduct background checks.
Second, when I work with libraries and other not-for-profit organizations who are considering using volunteers, who also have one or more unions representing their employees, I stress the need to work with the union(s) pro-actively to confirm that an activity performed under the volunteer policy is not regarded as replacing paid/union workers.
There are a number of ways to achieve this confirmation.
The most formal way would be accomplished through a broad exclusion clause in the union contract(s) so every program does not present an ad-hoc task (but that could be a hard thing to fight for at a negotiation). A sample clause for that could be:
It is understood between the Parties that volunteer service performed per the Library's "Volunteer Policy" to enable events and programs that are not part of the Library's Plan of Service are not regarded as replacing or supplementing union members.
However, if such a clause is not a part of the standing collective bargaining agreement, a simple exchange of emails, or a more formal signed memorandum addressing only one type of volunteer activity, can be used to confirm this understanding.
The goal in all cases is to have clarity about what service is being performed by the volunteers, and to be able to show an affirmative agreement that it is not negatively impacting the experience of the workers in the union (which risks assertions of breaching the contract). Since the perception of "negative impact" (and breach) can vary from place to place, this is not an understanding to pursue after-the-fact nor without a solid understanding of the legalities and subtleties of the situation.
Third, even if a union is amendable to it, I would caution a library against using volunteers for any service that is part of a library's Plan of Service, since that can undercut the data needed to support adequate state/local funding. Volunteers can be invaluable assets, but a library should always be able to function as required by law without them.
Fourth, if all the other cautions and no-no's listed above check out, it is vital to have a very clear agreement with the collaborating organization outlining the nature of the service, and each parties' roles and responsibilities for it. This ensures the risks and liabilities posed by offering any program to the public are properly balanced, and the library isn't taking risks for the actions of volunteers provided by another organization. I know it sounds impolite, but when it comes to volunteer services from a third-party, a not-for-profit must look a gift horse in the mouth.
In many ways, it's a new world out there. For libraries seeking to innovate and work with other organizations to co-produce new programs, the above-listed cautions can set the stage for using volunteers without worrying about violating a union contract.
Thank you for a good question.
 (Onteora Cent. Sch. Dist. v Onteora Non-Teaching Empls. Asso., 79 AD2d 415 [3d Dept 1981])
 After the original decision cited in footnote 1, this case takes a lot of twists and turns through different rulings involving the education law and the authority of arbitrators. But the takeaway for purposes of this answer is: "Yes, use of volunteers can violate a CBA."
 For this reason, whenever possible, an attorney who knows the volunteer policy, knows the details about the service to be performed, and knows the union contract, should be consulted in advance.
 Of course, libraries and other organizations can host volunteer services (have them on site, but not co-sponsor them) provided by other organizations (such as Literacy Volunteers) without having to worry about these issues quite as deeply. "Hosting," rather than "collaborating" is a way to work with other organizations (and their volunteers) while not exposing a library to an assertion of violating the labor law, a CBA, or incurring unnecessary liability.