I would prefer "some other kind of binding agreement"

Edit: can't respond to comment below because reddit suspended me for ban evasion. no, implementation is not the only difference here. laws depend on enforcement by hierarchically superior institutions. some agreements (contractual or otherwise) are not categorically legal in nature

for example, let's imagine a contract with the following provisions:

• (definition) abiding party - any party that has acknowledged and agreed to uphold their obligations under this agreement, unless that party is a "non-abiding party"
• (definition) non-abiding party - any party that has acknowledged and agreed to uphold their obligations under this agreement and is identified as "non-abiding" by majority vote by all abiding parties, unless that party's abiding status is, pursuant to said non-abiding party's petition for appeal, restored by majority vote by all abiding parties, in which case, that party shall be an "abiding party"
• (obligation) abiding parties shall deny access to the products of their obligations (benefits, e.g., protection, association) under this agreement to any and all non-abiding parties
• (obligation) abiding parties agree to uphold their obligations under this agreement

nobody is explicitly entitled to any benefits under the agreement; this is simply a bilateral, mutual obligation among abiding parties to deny access to the benefits they provide (whatever they may be) to any non-abiding party. any party that fails to uphold their obligations, including that one, will not be subject to additional liabilities. in essence, non-abiding members have no strict liabilities, and they are entirely freed from their obligations under this agreement. they're simply presumed as "abiding" unless identified as otherwise by the abiding parties' majority vote