Question:
If a person desecrated Shabbos because he sincerely believed there was a situation of pikuach nefesh, but afterward discovered that there was never any actual danger, does he require a tikkun or repentance for his actions?
Answer:
No. If at the time of the incident the person genuinely believed that there was a possibility of danger to life and acted accordingly, then he acted properly and does not require any tikkun.
Examples include calling an ambulance for someone who appeared to be in a potentially dangerous medical condition, only to later discover that nothing was wrong, or turning off a hot water boiler left on for too long that appeared potentially dangerous, only to later learn that built-in safety mechanisms removed any risk. In all such cases, the action was taken based on a sincere assessment of possible pikuach nefesh.
The Poskim strongly oppose requiring a tikkun in these situations. If people were told that they must perform repentance each time they later discover that the danger was not real, they may become hesitant in future cases to desecrate Shabbos when a life may genuinely be at risk. Such hesitation could itself endanger lives.
Accordingly, the halachic evaluation is based on the information reasonably available at the time of the decision, not on facts discovered afterward. If the situation reasonably appeared dangerous then, the person acted correctly then, even if hindsight later reveals that there was no actual danger.
Certainly, people should continue to educate themselves regarding what situations constitute genuine danger and what do not. Nevertheless, gaining greater knowledge afterward does not retroactively transform a proper act of pikuach nefesh into a transgression. Just as physicians continually learn and may later discover that a condition they once considered life-threatening is actually not dangerous, so too their earlier actions taken to protect life remain fully justified.
Sources:
Admur 328:2 and 17; Michaber 328:2 and 15; Yoma 83a–84b; Admur 334:28; Darkei Moshe 334:7; Or Zarua 2:38; Chavos Yair 236; Shaareiy Teshuvah 334:2; Tashbatz 1:54; Shulchan Shlomo 334:4; Chasam Sofer 85; M”B 334:78 in name of Nezer Yisrael in name of Zechor Leavraham; Piskeiy Teshuvos 334 footnote 117