Q: Is it constitutional for an approved pickleball paddle list which is based on lab measured acoustic noise level?

A: You raise some valid points about the subjectivity and variability of acoustic noise levels from pickleball paddles. Whether an approved paddle list based on lab-measured noise would be constitutional is a complex legal question that would likely depend on the specific circumstances and how the law is written and applied.

A few key considerations:

1. Rational basis - Generally, laws must have a rational basis and legitimate government purpose to be upheld. Reducing noise pollution could potentially qualify, but it would need to be shown that the approved paddle list rationally serves that purpose.

2. Consistent and non-arbitrary enforcement - As you note, there are many variables affecting real-world noise levels. For the law to be constitutional, it would likely need to be enforced consistently and not arbitrarily. Inconsistent or arbitrary enforcement could violate due process.

3. Overbreadth - If the restrictions substantially limit the use of equipment without meaningfully serving the purpose of noise reduction, it could potentially be challenged as unconstitutionally overbroad.

4. Vagueness - The law and testing standards would need to be written clearly enough that paddle manufacturers and players can understand how to comply. Vague laws can be unconstitutional.

5. Undue burden on interstate commerce - If the law places substantial burdens on interstate commerce (e.g. paddle makers can't sell in that state) without sufficient local benefit, it could potentially violate the dormant commerce clause.

Ultimately, it would likely come down to the details of the law, the strength of the government's interest in noise reduction, and whether the approved paddle list is a properly tailored means of rationally advancing that interest. Both sides would have arguments, and it could require litigation to hash out. Consulting local legal experts would be advisable for anyone actually facing this situation. But in general, the government does have pretty broad authority to regulate for public health and welfare, as long as it does so in a rational, consistent, and clearly defined way.