Daguerres work on his process had commenced at about the same time as Talbots earliest work on his salted paper process. In 1839, Daguerres agent applied for English and Scottish patents only a matter of days before France, having granted Daguerre a pension for it, declared his invention "free to the world." The United Kingdom, along with the British Empire, therefore became the only places where a licence was legally required to make and sell daguerreotypes. This exception is now usually regarded as both an expression of old national animosities, still smouldering just 24 years after Waterloo, and a reaction to Talbots patent. Talbot never attempted to patent any part of his printed-out silver chloride "photogenic drawing" process and his calotype patent was not registered in Scotland.
In February 1841, Talbot obtained an English patent for his developed-out calotype process. At first, he sold individual patent licences for £20 each; later, he lowered the fee for amateur use to £4. Professional photographers, however, had to pay up to £300 annually. In a business climate where many patent holders were attacked for enforcing their rights, and an academic world that viewed the patenting of new discoveries as a hindrance to scientific freedom and further progress, Talbot's behaviour was widely criticised. On the other hand, many scientists supported his patent and they gave expert evidence in later trials. In addition, the calotype method was free for scientific uses, an area that Talbot himself pioneered, such as photomicrography. One reason Talbot later gave for vigorously enforcing his rights was that he had spent, according to his own reckoning, about £5,000 on his various photographic endeavours over the years and wanted to at least recoup his expenses.
In 1844, Talbot helped set up an establishment in Russell Terrace (now Baker Street), Reading, for mass-producing salted paper prints from his calotype negatives. The Reading Establishment, as it was known, also offered services to the public, making prints from others' negatives, copying artwork and documents, and taking portraits at its studio. The enterprise was not a success.
In 1851, the year of Daguerre's death, Frederick Scott Archer publicised the wet collodion process, which made it practical to use glass instead of paper as the support for making the camera negative. The lack of detail often criticised in prints made from calotype negatives was overcome, and sharp images, comparable in detail to daguerreotypes, could finally be provided by convenient paper prints. The collodion process soon replaced the calotype in commercial use, and by the end of the decade, the daguerreotype was virtually extinct as well.
Asserting a very broad interpretation of his patent rights, Talbot declared that anyone using the collodion process would still need to get a calotype licence.
In August 1852, The Times published an open letter by Lord Rosse, the president of the Royal Society, and Charles Lock Eastlake, the president of the Royal Academy, who called on Talbot to relieve the patent pressure that was perceived as stifling the development of photography. Talbot agreed to waive licensing fees for amateurs, but he continued to pursue professional portrait photographers, having filed several lawsuits.
In 1854, Talbot applied for an extension of the 14-year patent. At that time, one of his lawsuits, against photographer Martin Laroche, was heard in court. The Talbot v. Laroche case proved to be pivotal. Laroche's side argued that the patent was invalid, as a similar process had been invented earlier by Joseph Reade, and that using the collodion process did not infringe the calotype patent in any case, because of significant differences between the two processes. In the verdict, the jury upheld the calotype patent but agreed that Laroche was not infringing upon it by using the collodion process. Disappointed by the outcome, Talbot chose not to extend his patent.