illegal substitution penalty
 

Team B is shooting free throws for a foul.

After the first freethrow, team A makes substitutions, and one player for team A just runs on the court and replaces another at the lane line during this, thus becoming an illegal replacement. The table calls me over to tell me about the problem, before the second free throw is started.

What is the penalty??

See rule 10-2

cool, I did it right, thanks

Impatient Substitute ...
 

If a substitute enters the court without reporting to the scorer; and without being beckoned by an official, except between periods, then a technical foul shall be charged to the substitute. Each illegal substitute gets one technical foul per instance, whether they didn’t report, or entered the court without being beckoned, or both. However, two technical fouls are not charged if the illegal substitute doesn’t report and enters without being beckoned. A substitute technical foul is charged if recognized by an official before the ball becomes live following the first dead ball. Once the ball becomes live, the substitute is a legal player at that point, the foul is not penalized. Remember, the ball becomes live when: on a jump ball, the tossed ball leaves the referee’s hand; on a throw-in, it is at the disposal of the thrower; and on a free throw, it is at the disposal of the free thrower.

Additional Options ???
 

A technical foul is certainly warranted here, however, there are other approaches.

One approach is to give a strong "stop sign" to said substitute if he's trying to illegally enter while the foul is being reported.

Another approach is to tell the illegal substitute to go back to the table, and tell the player who went out to get back on the lane line. Then beckon in the substitute. He'll be so embarrassed that he probably won't do it again.

The three approaches depend on the age level of the players, and the usual approach that's taken in your neck of the woods. We're very patient here in my little corner of Connecticut. In thirty years, I've never seen a technical foul charged for this infraction in any high school game, varsity, or subvarsity, ever. We never let this go. We always address it. We usually take the "stop sign" approach.

But remember, as St. Ambrose use to say, "When in Rome ... ".

^ +1