Originally Posted by
SkiAdcock
Huh?

As a practical matter, it may turn out that those subject to this passport blacklisting may keep using their already-issued-and-delivered US passports unless and until those passports are provided to a State Department employee in the ordinary course of things -- such as the bearer of the passport seeking additional passport services from a State Department employee -- whereafter they would be seized/cancelled. In other words, the passport revocation may end up being conditioned upon the bearer of the passport voluntarily surrendering the passport to a State Department employee.
Example: Let's say a "seriously delinquent taxpayer" who is legally a free person has a US passport already issued in October 2015 traveled from the US in November 2015. This person returns to US in May 2016 using their US passport. The person present their US passport to CBP, and CBP hands it back to the "seriously delinquent taxpayer" after admitting the person. The person then uses the passport to fly back out of and into the passport for the remaining duration of the passport as indicated by the original, printed expiration date of the passport. However, if the "seriously delinquent taxpayer" takes in their passport to the US to a US Embassy/consulate to seek any passport services, then the State Department employee would seize and revoke the passport.
I'm not sure this is how it would work, but (perhaps due to privacy reasons and other stipulations applicable to different government agencies and what can and cannot be shared or passed on between government agencies), it could be that the revocation could only take place after a State Department employee gets their hands on the passport of such person, with CBP only handing over the passports to State in rather more extraordinary circumstances than that of a "seriously delinquent taxpayer", legally free US citizen presenting a passport for use with CBP and other non-State Department governmental employees.
Also, even after a law passes, it takes time for implementation by the Executive Branch. For example:
Originally Posted by CNN.com
A new law took effect in December 2008 that prohibits anyone convicted of sex tourism from receiving a U.S. passport. However, the report said, the Department of State was not even aware of the law until April of this year [2010] after the GAO "brought this statute to its attention."
"When Congress passes a law and the president signs it, then the Executive Branch needs to execute it," Grassley said in a statement. "I'm shocked that GAO had to inform the State Department that Congress made individuals convicted of sex tourism ineligible for passports back in December 2008. It's inexcusable that the State Department did nothing to enforce that provision for 14 months. Since someone who is late on child support payments cannot receive a passport, then surely these criminals should also be stopped from traveling internationally."
[I added "[2010]" above to make it clear in which year the article above was published.]
For a law to be implemented by the bureaucracy involves certain administrative steps. Those required, administrative implementation steps can take months or years before an administrative procedure required by law can be implemented.
Watch the Federal Register to see how and when this actually gets implemented by the Administration.