Perhaps this is a US / UK difference, but I think you mean prospectively rather than proactively (Google also seems to suggest the latter is not a common use).

What is the relevance of the claim “Clinton is one of the more infamous examples”?

@JBentley The two have distinct meanings. Prospective describes something which will likely happen in the future, something expected. Biden has been the prospective next President for a while, arguably even before he became President-elect!. As if to make that point, Mexico's ambassador called Biden '“prospective” President-elect' on Nov. 10: She expected that status but wasn't quite sure yet. Proactive, by contrast, means a current action -- but one targeting future events.As opposed to simply re-acting to past events. The pardon would be current, targeting future prosecution.

@gerrit I simply googled lame-duck pardons, and Clinton came up as a prominent example. He also pardoned a family member, so it seemed a good example. And then it hopefully added a bi-partisan touch.

@Peter-ReinstateMonica You're talking about the ordinary English language meaning of the words, but I'm talking about the legal definitions. A prospective ruling is one that rules over something which will hypothetically happen in the future. A proactive ruling is not something I have ever heard of... again, this could be a jurisdictional difference (but while I found plenty of results for "prospective pardon" I found very few for "proactive pardon" so I suspect it is not a correct usage in the US either).

@JBentley You are right. The "proactive faction" seems to be the popular news sites etc, while "prospective" is used in the law literature, e.g. the very first library of congress link that pops up, which is by the way answering the question here. Now I'm not using the specific term "proactive pardon" in the title, so I let it stand for now.

It's not "official" until the Electoral College votes in December and (technically) until the House of Reps meets to certifies their vote January.

@TylerH I was not aware that the Electoral College declares a lame duck President! ;-)

@Peter-ReinstateMonica Biden was already president-elect on Nov 10. He became president-elect once polls closed on Nov 3. Just because he hadn't been determined to be president-elect doesn't mean wasn't, just as Mark Felt was Deep Throat before he admitted it.

"President Trump's administration has just formally started the transition process."- on what basis do you state this.

@user2617804 "As the Administrator of the U.S. General Services Administration, I have the ability under the Presidential Transition Act of 1963, as amended, to make certain post-election resources and services available to assist in the event of a presidential transition. See 3 U.S.C. §102 note (the"Act"). I take this role seriously and, because of recent developments involving legal challenges and certifications of election results, am transmitting this letter today to make those resources and services available to you." (ctd.)

@user2617804 (ctd.:) From gsa.gov/cdnstatic/2020-11-23_Hon_Murphy_to_Hon_Biden_0.pdf. Why did you ask? Were you in doubt?

That is not a statement from the Trump administration.

@user2617804 - Trump himself said "I am recommending that Emily [the GSA] and her team do what needs to be done with regard to initial protocols, and have told my team to do the same." So yes, while the GSA is an independent agency you could argue isn't part of the administration, Trump has also told his team to get started. I don't think we can reasonably construe "my team" not to include his administration.

@user2617804 Errr... "GSA was established by President Harry Truman on July 1, 1949 to streamline the administrative work of the Federal Government." (gsa.gov/about-us/mission-and-background/our-missions-evolut‌​ion) !? The GSA is a prototypical part of the [Trump] administration. (The Trump administration does not only consist of people named Trump, even if it sometimes gives the impression.)

@Peter-ReinstateMonica - (LOL about "people named Trump.") I think the fact it's an independent agency is ever-so-slightly relevant, but I don't think the distinction was really worth drawing in the first place and in any case, you don't get much more "Trump Administration" than Trump himself, quoted above, so either way, your claim about the Trump Administration having started working on transition is well-supported. :-)