Originally Posted by
FlyingFreeYupie
If they deny me boarding, do I have a valid EC261 claim as they are going against the law of the country I am a citizen of?
No.
You don't qualify to take the return flight to LIS, i.e. TAP has good grounds for denying you to fly.
Whether this new practice/policy of TAP is contrary to Portuguese law has nothing to do with EC Reg. 261/04.
In general claims for compensation during Covid-19 times are not entertained and will lead nowhere.