State of Languages in the Federation

[The Hanuk Kai]

^Which may explain why Chekov believes everything is Russian in origin.

 

[Alidar Jarok]

T'Pol likely was actually speaking English given UTs weren't as common back in the day.

She specifically says she's speaking English in Broken Bow (something like "I was instructed to speak English") after Hoshi tried to speak Vulcan to her.

I don't think we can extrapolate the extent that everyone speaks English on Earth, but it might be that English is advantageous to learn in Starfleet. I don't think it's ever entirely possible to reconcile the random times Klingon shows up, but I'd suggest that Worf is speaking English rather than being translated. Quark, on the other hand, apparently speaks no English and I suspect that the Bajorans (and Odo) are the same way.

Of course, it's a plot device done for convenience 95% of the time, so I wouldn't think too much about it.

 

[FreddyE]

Actually I think it would be save to assume that Odo speaks Cardassian, since he "grew up" in the lab of a cardassian scientist.

 

[The Hanuk Kai]

Actually I think it would be save to assume that Odo speaks Cardassian, since he "grew up" in the lab of a cardassian scientist.

If not, he is an officer of the Cardassian court, suggesting a higher degree of familiarity with Cardassian practices (including language).

 

[Chris3123]

There was a episode of Farscape where everyone's translator microbes stopped working, none of them spoke any of the other's languages.

This seems like an obvious plot for a Star Trek episode, its strange how its never happened.

I once pitched a Voyager ep in which the UT broke down and suddenly Neelix couldn't talk to anyone. Alas, it didn't sell, but maybe I can recycle it as short story or subplot someday . . . ?

There actually was an episode (the two-parter "Basics") where the crew was without UT, but Neelix and Kes were somehow still able to communicate normally. Though in-universe I suppose it's possible that they both learned to speak perfect English by that point. Still, sloppy writing.