Here in McGarr Solicitors (for inhabitants of the USA, a solicitor is a lawyer), we spell “intellectual” with three els. We think to spell it “intelectual”, as some colleagues have (and do), is wrong.
I was once part of the Robert Maxwell publishing empire; great care was taken then to ensure errors were weeded out before they reached the public. An author’s work was brought into the printing process by being fully re-typed. Then it was composed and galley proofs were printed. A proof-reader would then read it, checking for errors by the author and the printers. Spelling errors would be corrected, but printing errors might be more difficult to spot. We would aspire to notice a full stop of a different typeface in the text. (Not impossible, especially if the typeface was at 24 point.)
I am, consequently, indulgent of errors in an age where some social/management structures have become flat (or even, have been flattened!). Also some words are very difficult to spell, like “independent” (or is that “independant”?). However, when you choose to use certain big words like “intellectual”, you must get them right. Would anyone have paid much attention, say, if Jean-Paul Sartre had written;
We intelectuals must stand together on this issue!
Accordingly, do not write (or leave uncorrected) “…we…specialise in intelectual property law”.