Robert Downey Jr. has made Sherlock Holmes popular again. Or has he?

CBS says it's working on what it's calling a modern-day take on the 19th century detective as part of its pilot slate for next summer. The network has reportedly bought the concept from Timberman-Beverly Productions, according to Deadline.com, which will be produced by CBS TV Studios.

Yet, it's not the first time in recent memory that someone has attempted to make a modern-day version of Sherlock Holmes. In fact, "Doctor Who" showrunner Steven Moffat did it just recently with a popular BBC miniseries that was recently up for an Emmy through its broadcast on PBS.

"Dear CBS, a modern-day Sherlock Holmes?" Moffat tweeted when the news was first announced. "Where, oh where, did you get that idea?"

Moffat ended the Tweet with a polite word of warning: "We'll be watching."

Moffat co-created a modern-day version of the show with Mark Gatiss that stars Benedict Cumberbatch in the title role and Martin Freeman as Dr. John Watson. It was nominated for four Emmys, including Outstanding Writing, but did win a TCA Award as well as a Peabody.

Timberman-Beverly Productions appears to have no connection to the Moffat version at all, so whatever CBS is working on would apparently be outside of what was already done in Britain. And it is possible that two totally separate modern-day versions of the show could exist without infringing on each other, which would mean that more details would have to come out before any action could be taken.

But even if it was similar, what course of action would BBC Worldwide have? That's a question that would have to be left up to the lawyers if it ever does get to that point. Much of what Moffat and Gatiss created pays homage to the original Sir Arthur Conan Doyle stories, so if a CBS version were to do the same thing, it's hard to tell if that would be considered a direct copy of the Moffat version, or simply other producers taking the same path that they did.

What might be more interesting is the fact that while Sherlock Holmes is considered public domain in its home of Great Britain, in the United States, it's still under copyright protection until at least 2023. A 1976 law allowed heirs to copyrightable material to reapply for copyrights, which the heirs of Conan Doyle did. No production -- not even the Robert Downey Jr. film -- can move forward without being licensed from the estate. So it's assumed that Timberman-Beverly also received a license to continue with a modern take.

Timberman-Beverly has been busy in recent months. It got its start producing "Justified" for FX, and is offering two new series to CBS that are premiering this fall: "Unforgettable" and "A Gifted Man."