Law firms and other businesses are using geofencing to close in on potential customers. While this is an exciting area of marketing for many, some are calling it intrusive.

What’s geofencing? It’s defined as “the use of GPS or RFID technology to create a virtual geographic boundary, enabling software to trigger a response when a mobile device enters or leaves a particular area.”

Citing information from Philadelphia public radio station WHYY, Ars Technica reports that some area firms are using the technology to target mobile ads to those waiting for hospital emergency room care. Once a device has “jumped” the geofence, ads could continue to target the device long after the patient has left the hospital.

Says Ars, “privacy experts are raising the alarms.” Massachusetts Attorney General Maura Healey expressed her concern to WHYY over the exploitation of private medical information, especially when it’s gathered without the consumer’s knowledge or consent.

In 2017, after a Christian pregnancy counseling and adoption agency hired a digital firm to target ads to anyone entering reproductive health facilities, Healey’s office barred the practice, calling it digital harassment that also violated the state’s consumer protection act.

Overall, however, geofencing in hospitals is not illegal, and the interest among law firms continues. In fact, this type of targeting is among the fastest-growing areas for some marketing firms.

While some consumers may feel intruded upon, others may find the ads timely and useful, which is exactly what law firms and other businesses are hoping for.