Reese Witherspoon is taking some legal heat for a dress giveaway to teachers during the early days of the pandemic, and the lawsuit reads like the ultimate case of no good deed goes unpunished.

Three women are putting together a class-action lawsuit against Reese and her Draper James clothing company for their highly-publicized offer on Instagram in early April, which stated … “Dear Teachers: We want to say thank you. During quarantine we see you working harder than every to educate our children. To show our gratitude, Draper James would like to give teachers a free dress.”

So instead, according to the lawsuit, the nearly 1 million teachers who provided their personal info were entered into a lottery with a slim chance of winning … when they all believed they were getting free dresses.

The women suing point out that the total cost of the 250 dresses to be given away would only come out to an “estimated paltry $12,500 in actual cost” to Reese and her company … “at a time when other individuals of [Reese] Witherspoon’s renown were offering millions of dollars to COVID-19 victims.”

Translation: Yes, you were charitable, but we wanted you to be WAY more charitable. Wow.

The lawsuit alleges Reese and her company also benefited from the publicity of the giveaway — including shout-outs on “Today” and “Good Morning America.”

Draper James’ attorney Theane Evangelis tells TMZ … “This lawsuit is an unjust attempt to exploit Draper James’ good intentions to honor the teacher community by gifting hundreds of free dresses. The fact that supplies were limited, such that a free dress could not be provided to every teacher who responded, was disclosed and is no basis for a lawsuit.”

She continues, “Draper James looks forward to defending this case, to continuing its efforts to acknowledge the extraordinary contributions made by teachers during this time of need, and to being vindicated in court.”

The women are suing on behalf of all participants who accepted the Draper James deal … and are seeking damages.