ABC is a multinational enterprise (MNE) incorporated in State X. ABC entered into a joint venture agreement with XYZ, an MNE incorporated in State Y, to jointly produce a new line of hydraulic equipment in ABC's new factory in State Z, a developing nation. ABC & XYZ have mutually agreed to have the law of State Y govern any disputes or concerns arising under the joint venture agreement. Shortly after the conclusion of the agreement, a wiring defect in ABC's factory caused it to burn to the ground, killing five tourists in the immediate vicinity who were nationals (citizens) of State Q. XYZ, fearing bad publicity, sued ABC to rescind the joint venture agreement. X,Y, & Z are all common law states, while Q is a civil law jurisdiction.

In this scenario, there are several legal issues and considerations to discuss:

1. Choice of law: The joint venture agreement between ABC and XYZ has established that the law of State Y will govern any disputes or concerns arising under the agreement. This means that if any legal issues arise between ABC and XYZ, the courts of State Y will apply State Y's laws to resolve the dispute.

2. Wiring defect and factory accident: The wiring defect in ABC's factory caused it to burn down, resulting in the unfortunate death of five tourists who were nationals of State Q. This accident raises issues of personal injury and potential liability for ABC.

3. Jurisdiction: The incident occurred in State Z, a developing nation. It is important to determine which jurisdiction's courts will have authority to handle legal proceedings related to the accident and any subsequent lawsuits.

4. State Q's legal system: State Q is described as a civil law jurisdiction, while States X, Y, and Z are common law states. This difference in legal systems may impact the legal proceedings and potential remedies available in State Q, particularly for the families of the deceased tourists.

5. XYZ's lawsuit: XYZ, concerned about potential bad publicity, has decided to sue ABC to rescind the joint venture agreement. This raises issues of breach of contract and the potential consequences for ABC in relation to the agreement.

To address the specific question, it is important to consult legal professionals from each relevant jurisdiction and assess the applicable laws and regulations. It may require engaging legal experts in State Y to determine the validity of XYZ's lawsuit and understand its potential outcomes. The complexity of the case suggests that an in-depth legal analysis and professional guidance would be necessary to fully comprehend the consequences and potential steps forward for ABC and XYZ.