Müge Fazlioglu, IAPP principal researcher, privacy law and policy, has been tracking these developments. She described an increasingly complex patchwork of compliance for organisations working in the US.

“The applicability of each US state privacy law can be assessed through a multistep process as each state law has a unique scope based on variety of thresholds,” she told Computer Weekly. “These thresholds are related to entity’s jurisdiction, revenue, volume of personal data processing and revenue derived from the sale of personal data.”

To dig deeper into the extent to which the laws differ, five different thresholds in the US now exist for processing resident’s personal data. These include no threshold in Nebraska and Texas; 25,000 or more unique consumers in Montana; 35,000 in Connecticut, Delaware, Maryland, New Hampshire and Rhode Island; 100,000 in California, Colorado, Indiana, Iowa, Kentucky, Minnesota, New Jersey, Oregan, Utah and Virginia; and 175,000 in Tennessee. So, any organisation holding data on any Texas residents becomes subject to applicability, but they must hold data on 0.6% of the population of Maryland, or 3.3% of the population of tiny Delaware.

Then there are thresholds for the sale of personal data. Here, again, Nebraska and Texas are strictest, ruling that the control, processing or sale of any personal data is subject to state privacy laws, albeit with exemptions for small businesses. Meanwhile in California, organisations fall in scope if they control or process any personal data and derive 50% or more of their revenues from the sale of data. Colorado and New Jersey both include population thresholds again – 25,000 unique consumers or more, and in-scope organisations derive any revenue or discount on the price of any goods or services from the sale of personal data.

When it comes to exemptions, each of the 19 state laws excludes various entities and types of data held by them – most commonly, government agencies, non-profits and higher education institutions; and organisations already subject to national, sectoral legislation, such as the Health Insurance Portability and Accountability Act (HIPAA).

Differences again abound. For example, the laws of Colorado, Delaware, Minnesota, Montana, New Jersey and Oregon do not exempt non-profits. California and Maryland do exempt non-profits but do not exempt higher education institutions, and so on. Nuances exist even here – Delaware, for example, exempts only some non-profits and its laws don’t apply to those than handle data held by non-profits working with victims of child abuse, domestic violence, human trafficking or sexual assault. Neighbouring Maryland exempts those that process or share personal data to assist first responders in emergency situations, or law enforcement investigating fraud or insurance-related crime.

When it comes to business obligations under state privacy laws, all states require regulated entities to provide consumers with privacy practice disclosure notices – California asks for this at the point of collection, and all bar Rhode Island and Utah impose minimisation and purpose limitations on the collection or processing of data. This typically restricts the collection, use, retention and sharing of consumer data to what is adequate, relevant and reasonably necessary. Most states – bar Iowa and Utah – require data protection impact assessments (DPIAs), but in Delaware, Indiana and Virginia, DPIAs are specifically required for targeted advertising, the sale of personal data or individual profiling.

Naturally, all states require consent for processing of sensitive data, but again they define varying categories of data as sensitive. Most state laws cover a standard dataset that will be familiar to most, classing children’s data, data on ethnic background, religion, and sexual orientation as sensitive. However, some states go further, with Maryland and Oregon also recognising information on national origin as sensitive, while five states – Connecticut, Delaware, Maryland, New Jersey and Oregon – include data that might reveal an individual’s status as non-binary or transgender.

Maryland, meanwhile, has the only state level law that does not classify mental or physical health data as sensitive, whereas California ploughs a unique furrow and classes philosophical beliefs as a protected category, protecting existentialists, logical positivists, nihilists and stoics alike.

Finally, turning to consumer rights to access, correct and delete data held on them, things are a little simpler but there are still differences to account for. In all states consumers can access, correct and delete data – bar Iowa, where they cannot correct it; and Indiana, where they can correct it only if they have provided it in the first place.